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Tamluk Hamilton High School | School Test Question Paper | Target Book

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Book Name : Target Book
Paper Type : School Test Question Paper (2024 – 2025)
Paper Category : Madhyamik Suggestion
School : Tamluk Hamilton High School

Question – 1

Choose the correct answer for each of the following questions: [1 × 6 = 6]

(i) If the ratio of a principal and its amount in 1 year is 25 : 28, the rate of interest per annum is:

(a) 3 %

(b) 12 %

(c) 10 5\over7 %

(d) 8 %

Answer

(b) 12 %

Explanation:

Amount (A) = 28x

Principal (P) = 25x

Time (T) = 1 year

or, 28 = 25 × (1 + R \over 100)

or, 28 \over 25 = (1 + R \over 100)

or, 28 \over 25 – 1 = R \over 100

or, 3 \over 25 = R \over 100

or, R = 3 \over 25 × 100 = 12 %

(ii) The condition of being two roots of the equation ax² + bx + c = 0 are opposite in sign is:

(a) b = 0

(b) b < 0

(c) c/a < 0

(d) c/a > 0

Answer

(c) c/a < 0

(iii) The lengths of radii of two circles 3 cm and 4 cm and distance between two centres is 10 cm, numbers of common tangents of two circles are:

(a) 0

(b) 2

(c) 3

(d) 4

Answer

(d) 4

(iv) If sin A + sin B + sin C = 3, where 0 ≤ A, B, C ≤ 90°, then the value of sin A + B + C\over 6 is:

(a) 0

(b) 1\over 2

(c) 1\over √2

(d) 1

Answer

(c) 1\over √2

Explanation:

sin A + sin B + sin C = 3

sin A = 1 sin B = 1 sin C = 1
or, sin A = sin 90º

or, A = 90º

or, sin B = sin 90º

or, B = 90º

or, sin C = sin 90º

or, C = 90º

sin A + B + C\over 6 = sin 90º + 90º + 90º\over 6

= sin 270º\over 6

= sin 45º = 1\over √2

(v) Determine the ratio of the volumes of a solid right circular cylinder, a solid right circular cone, and a solid sphere of equal diameter and equal height:

(a) 3 : 2 : 1

(b) 3 : 1 : 2

(c) 2 : 3 : 1

(d) 1 : 2 : 3

Answer

(b) 3 : 1 : 2

Explanation:

Vcylinder = πr²h = 2πr³

Vcone = 1\over3πr²h = 2\over3πr³

Vsphere = 4\over3πr³

Vcylinder : Vcone : Vsphere = 2πr³ : 2\over3πr³ : 4\over3πr³

= 2 : 2\over3 : 4\over3

= 1 : 1\over3 : 2\over3

= 3 : 1 : 2

The ratio of the volumes is 3 : 1 : 2.

(vi) The median of the data 2, 8, 2, 3, 8, 5, 9, 5, 6 is:

(a) 8

(b) 6.5

(c) 5.5

(d) 5

Answer

(d) 5

Explanation:

The given data is: 2, 8, 2, 3, 8, 5, 9, 5, 6.

Arranging in ascending order: 2, 2, 3, 5, 5, 6, 8, 8, 9.

Median position = \text{n + 1}\over2 = \text{9 + 1}\over2 = 5

The 5th value in the ordered data is 5.


Question – 2

Fill in the blanks (Any Five):

(i) Two types of partnership business are ______ and ______.

(ii) If x is proportional to 1/y and y is proportional to 1/z, then x is proportional to ______.

(iii) Cyclic parallelogram is a ______ figure.

(iv) The value of cos 9° cos 18° cos 36° cos 72° cos 90° cos 144° is ______.

(v) If the numerical values of volume and lateral surface area of a right circular cylinder are equal, then the length of the diameter of the cylinder is ______ unit.

(vi) From two types of Ogives, the value of ______ is determined.

Answer

(i) General partnership and limited partnership

(ii) z

(iii) Rectangle

(iv) 0

(v) 4 units

(vi) Median


Question – 3

State whether True or False (Any Five):

(i) Conjugate surd of √5 + √3 is √5 – √3.

(ii) A started a business with ₹10,000; after 6 months, B joined the business with ₹20,000. At the end of the year, the profit share of each of them will be equal.

(iii) If 0° < θ < 90°, then sin²θ = sin²20°.

(iv) Right circular cylinder has three surfaces.

(v) If the median of arranging the ascending order of data 8, 9, 12, 17, x+2, x+4, 30, 31, 34, 39 is 15, then the value of x is 21.

(vi) If lengths of two corresponding medians of two similar triangles are 5 cm and 7 cm respectively, then the ratio of the areas of triangles is 25 : 49.

Answer

(i) True

(ii) False

(iii) False

(iv) True

(v) True

(vi) True


Question – 4

Answer the following Questions (Any Ten):

(i) The rate of simple interest per annum reduces to 3 ¾ % from 4% and for this, a person’s annual income decreases by ₹ 60. Determine the principal.

Answer

Principal = P

Rate (r) = 4 % – 3 ¾ = 1\over 4 %

Interest (I) = ₹ 60

Time (t) = 1 year

P = \text{I} × 100\over \text{r × t} = 60 × 100\over {1\over 4} × 1 = ₹ 24,000

(ii) In a partnership business, the ratio of capitals of A, B, and C is 1\over6 : 1\over5 : 1\over4. If at the end of the year the profit of the business is ₹3700, find the profit share of C.

Answer

Ratio of capitals of A, B, and C = 1\over6 : 1\over5 : 1\over4

To simplify, take the LCM of the denominators (6, 5, and 4), which is 60. Multiply each term in the ratio by 60

= 1\over6 × 60 : 1\over5 × 60 : 1\over4 × 60

= 10 : 12 : 15

Sum of Ratio = 10 + 12 + 15 = 37

The profit of the business is ₹3700.

Profit of C = ₹ 15\over37 × 3700 = ₹ 1500

The profit share of C is ₹1500.

(iii) For what value of k, the sum of the square of the roots of the equation 6x² + x + k = 0 is 25\over26.

Answer

Sum of the roots (α + β) = –1\over6

Product of roots (αβ) = k\over6

Now, α² + β² = (α + β)² – 2αβ

= (-1\over6)² – 2 × k\over6

= 1\over36k\over3

or, 25\over26 = 1 - 12k\over36

or, 1 – 12k = 25\over26 × 36

or, 12 k = 1 – 900\over26

or, k = 26 - 900\over26 × 12

or, k = – 874\over312 = – 437\over156

(iv) Find out the simplest value of \sqrt{4+ \sqrt{15} } -{1\over2}\sqrt{10}

Answer

Given: \sqrt{4+ \sqrt{15} } -{1\over2}\sqrt{10}

= \sqrt{4 \times 4+ 4 \times\sqrt{15} \over4}{1\over2}\sqrt{10}

= {1\over2}\sqrt{16+ 4\sqrt{15}}{1\over2}\sqrt{10}

= {1\over2}\sqrt{(\sqrt{10})^2 + (\sqrt{6})^2+ 2\sqrt{10}\sqrt{6}} {1\over2}\sqrt{10}

= {1\over2} \sqrt{(\sqrt{10} + \sqrt{6})^2} {1\over2}\sqrt{10}

= {1\over 2} (\sqrt{10} + \sqrt{6}) {1\over2}\sqrt{10}

= {\sqrt{10}\over2} + {\sqrt{6}\over2} {1\over2}\sqrt{10}

= {\sqrt{6}\over2}

(v) In the adjoining figure, O is the center of the circle, OP ⊥ AB; AB = 6 cm, and PC = 2 cm. Determine the radius of the circle.

ABCD_is_a_cyclic_quadrilateral._AB_and_DC_are_extended_to_meet_at_P._Prove_that_PA_PB___PC_PD-removebg-preview (1)

Answer

PC = 2 cm

OP = r – 2

OB = r

PB = 1\over2AB cm = 3 cm

Applying pythagoras theorem:

OB² = PB² + OP²

or, r² = 3² + (r – 2)²

or, r² = 3² + r² – 4r + 4

or, 4r = 13

or, r = 3.25 cm

(vi) In Δ ABC, ∠ABC = 90°, and BD ⊥ AC. If BD = 8 cm and AD = 4 cm, then determine the length of CD.

Answer

In the right-angled triangle ABC, with ∠ABC = 90°, the altitude BD is drawn from the right angle B to the hypotenuse AC.

This divides AC into two segments AD and DC.

BD² = AD × DC

Given: BD = 8 cm and AD = 4 cm.

Substitute these values into the relation: (8)² = 4 × DC

64 = 4 × DC

DC = 64 ÷ 4

DC = 16 cm

Thus, the length of CD is 16 cm.

(vii) In the adjoining figure, O is the center of the circle, AB is the diameter, ∠AOD = 140°, and ∠CAB = 50°, then find ∠BED.

ABCD_is_a_cyclic_quadrilateral._AB_and_DC_are_extended_to_meet_at_P._Prove_that_PA_PB___PC_PD__1_-removebg-preview

Answer

Given that ∠AOD = 140°

∴ reflex ∠AOD = 360° – 140° = 220°

Again, the central angle produced by the arc ÂBD is reflex ∠AOD and angle in circle = ∠ACD

∴ reflex ∠AOD = 2∠ACD

or, 220° = 2∠ACD

∴ ∠ACD = 220°\over2 = 110°

Given that ∠CAB = 50°

Now, in ΔACE,

∠AEC + ∠EAC + ∠ACE = 180°

or, ∠AEC = 180° – 50° – 110° = 20°

Hence ∠BED = 20°

(viii) In Δ ABC, a parallel line to BC intersects the sides AB and AC at P and Q respectively. PB = AQ, AP = 9 units, QC = 4 units. Find the length of PB.

Answer

Let PB = x. Given that PB = AQ, we also have AQ = x.

From the given data:

  • AP = 9 units
  • QC = 4 units

Since P and Q lie on AB and AC respectively:

  • AB = AP + PB = 9 + x
  • AC = AQ + QC = x + 4

Because PQ is drawn parallel to BC, the triangles APQ and ABC are similar.

This gives us the proportion: AP / AB = AQ / AC

9 / (9 + x) = x / (x + 4)

9(x + 4) = x(9 + x) 9x + 36 = 9x + x²

9x + 36 = 9x + x²

36 = x²

Therefore: x = √36 = 6

Since PB = x, PB = 6 units.

(ix) If cos θ + sec θ = 2, then determine the value of cos2024θ + sec2024θ.

Answer

cos θ + sec θ = 2

or, cos θ + 1\over \text{cos θ} = 2

or, cos² θ + 1 = 2cos θ

or, cos² θ – 2cos θ + 1 = 0

or, (cos θ – 1)² = 0

or, cos θ – 1 = 0

or, cos θ = 1 and sec θ = 1

Now, cos2024θ + sec2024θ = (1) 2024 + (1) 2024

= 1 + 1 = 2

(x) The lengths of two adjacent walls of a room are 12 m and 8 m respectively. If the height of the room is 4 m, determine the area of the floor of the room.

Answer

The two given walls that meet at a corner (12 m and 8 m) represent the length and width of the rectangular floor.

Length = 12 m and Width = 8 m

Area = 12 m × 8 m = 96 m²

The height of the room (4 m) is not needed to find the area of the floor. The height would be relevant if we were asked for the volume of the room, but for the floor area alone, only the length and width matter.

Therefore, the area of the floor is 96 m².

(xi) Curved surface area of a solid sphere is S and volume V, then find the value of S^3\over V^2.

Answer

Given a solid sphere with radius r, we know:

Surface area S = 4πr²

Volume V = (4/3)πr³

Now, S^3\over V^2.

= (4πr²)^3\over ({({4\over3})}πr³)^2

= 64π³r⁶\over {({16\over9})}π²r⁶

= 64π\over {({16\over9})}

= 64π × 9\over 16

= 36 π

(xii) If the mean of the data x1, x2, x3, …, x50 is x̄, then find the value of (x1 – x̄) + (x2 – x̄) + … + (x50 – x̄).

Answer

Given that the mean of x1, x2, x3, …, x50 is x̄, we know:

x̄ = (x1 + x2 + x3 + … + x50) / 50

Consider the sum: (x1 – x̄) + (x2 – x̄) + … + (x50 – x̄)

Distribute the summation: = (x1 + x2 + … + x50) – 50x̄

Since x̄ is the mean: x1 + x2 + … + x50 = 50x̄

Substitute this: = 50x̄ – 50x̄ = 0

Therefore, the value of (x1 – x̄) + (x2 – x̄) + … + (x50 – x̄) is 0.


Question – 5

Answer any One of the following Questions:

(i) Rohan takes a loan of ₹2,40,000 from a bank for constructing a building at the rate of simple interest of 12% per annum. After 1 year of taking the loan, he rents the house at the rate of ₹5200 per month. Determine the number of years he would take to repay his loan along with interest from the income of the house rent.

Answer

Let after x years he will repayment the amount.

Interest of ₹ 240000 at 12% for x years

= \frac{240000 × 12 × x}{100} = 28800 x

Amount = Principal + Interest

= ₹ (240000+28800x)

Now, house rent for 1 year 12m = ₹ 5200 × 12

∴ House rent for (x – 1) yrs = ₹ 5200 × 12 × (x – 1)

= 62400 (x – 1)

According to the problem,

62400 (x – 1) = 240000 + 28800 x

or, 62400 x – 62400 = 240000 + 28800 x

or, 62400 x – 28800 x = 240000 + 62400

or, 33600 x = 302400

∴ x =\frac{302400}{33600} = 9

∴ After 9 years he will repay his loan with interest.

(ii) Srikanta and Soifuddin have started a partnership business together by investing ₹30,000 and ₹50,000 respectively. After 6 months, Srikanta has invested ₹4,000 more but Soifuddin withdrew ₹1,000 for personal need. If the profit at the end of the year is ₹19,000, calculate the profit share of each of them.

Answer

Investment of Srikanta = ₹30,000 × 6 + ₹34,000 × 6

= ₹ 384,000

Investment of Soifuddin = ₹50,000 × 6 + ₹49,000 × 6

= ₹ 594,000

Ratio of investments = ₹ 384,000 : ₹ 594,000 = 64 : 99

Sum of ratio parts = 64 + 99 = 163

Srikanta’s share = 64\over163 × 19,000 = ₹ 7,460

Soifuddin’s share = 99\over163 × 19,000 = ₹ 11,540


Question – 6

Answer any One Question:

(i) Solve: x - 2\over x + 2 + 6 x - 2\over x - 6 = 1, [x ≠ -2, 6].

Answer

x - 2\over x + 2 + 6 x - 2\over x - 6 = 1

or, (x - 2)(x - 6) + 6(x - 2)(x + 2)\over (x + 2)(x - 6) = 1

or, (x² – 8x + 12) + 6(x² – 4) = x² – 4x – 12

or, 7x² – 8x – 12 = x² – 4x – 12

or, 7x² – 8x – 12 – x² + 4x + 12 = 0

or, 6x² – 4x = 0

or, 2x(3x – 2) = 0

or, x = 0 or x = 2/3

(ii) If one root of the equation ax² + 5x + c = 0 is twice the other, find the value of b²/ac.

Answer

Let the roots be α and 2α

Sum of roots = α + 2α = –5\over a

or, 3α = –5\over a

or, α = –5\over 3a — (1)

Product of root = α × 2α = c\over a

or, 2α² = c\over a

or, α² = c\over 2a — (2)

Put α = –5\over 3a

(-5\over 3a)² = c\over 2a

or, 25\over 9a² = c\over 2a

or, 25\over 9a = c\over 2

or, 50 = 9 ac

or, ac = 50\over9

Now, b^2\over ac = 5^2\over {50\over9}

= 9\over 2


Question – 7

Answer any One Question:

(i) If x = √7 + √3\over√7 - √3 and xy = 1, then calculate the value of x² + xy + y²\over x² - xy + y².

Answer

x = √7 + √3\over√7 - √3 × √7 + √3\over√7 + √3

= (√7 + √3)²\over (√7)² - (√3)²

= 7 + 2√21 + 3\over 7 - 3

= 10 + 2√21\over 4

= 5 + √21\over 2

and y = 1\over x = 5 - √21\over 2

Finding (x + y) :

x + y = 5 + √21\over 2 + 5 - √21\over 2

= 5

Finding x² + y²: 

x² + y² = (x + y)² – 2xy

= (5)² – 2(1)

= 23

Now, x² + xy + y²\over x² - xy + y² = x² + y² + xy\over x² + y² - xy

= 23 + 1\over 23 - 1

= 24\over 22

= 12\over 11

(ii) If 3x – 4y ∝ √xy, then show that x² + y² ∝ xy.

Answer

(3x – 4y) ∝ √xy

or, (3x – 4y)² ∝ (√xy)²

or, 9x² – 24xy + 16y² ∝ xy

or, 9x² – 25xy + 16y² ∝ 0

or, 9x² – 16xy – 9xy + 16y² ∝ 0

or, x (9x – 16y) – y (9x – 16y) ∝ 0

or, (9x – 16y)(x – y) ∝ 0

or, (x – y) ∝ 0 —- (1)

Multiplying both sides by x + y

(x – y)(x + y) ∝ 0

or, (x + y) ∝ 0

We know, x³ + y³ = (x + y)(x² – xy + y²)

or, (x + y) = x³ + y³\over x² - xy + y²

or, x³ + y³\over x² - xy + y² ∝ 0

or, x³ + y³ ∝ 0

or, (x + y)(x² – xy + y²) ∝ 0

or, x² – xy + y² ∝ 0

or, x² + y² ∝ xy


Question – 8

Answer any One Question:

(i) If ay - bx\over c = cx - az\over b = bz - cy\over a, then prove that x\over a = y\over b = z\over c

Answer

ay - bx\over c = cx - az\over b = bz - cy\over a = k

or, ay - bx\over c = k

or, ay – bx = kc

or, ay - bx\over ab = kc\over ab

or, {y\over b} - {x\over a} = kc\over ab — (1)

cx - az\over b = k

or, cx – az = kb

or, cx - az\over ac = kb\over ac

or, {x\over a} - {z\over c} = kb\over ac — (2)

bz - cy\over a = k

or, bz – cy = ka

or, bz - cy\over bc = ka\over bc

or, {z\over c} - {y\over b} = ka\over bc — (3)

Adding (1), (2) and (3)

{y\over b} - {x\over a} + {x\over a} - {z\over c} + {z\over c} - {y\over b} = kc\over ab + kb\over ac + ka\over bc

or, kc\over ab + kb\over ac + ka\over bc = =

or, (a² + b² + c²)k\over abc = 0

or, k = 0 × abc\over (a² + b² + c²) = 0

From eq (1)

cx – az = kb

or, cx – az = 0 × b

or, cx = az

or, x\over a = z\over c —- (4)

From eq (2)

bz – cy = ka

or, bz – cy = 0 × a

or, bz – cy = 0

or, bz = cy

or, \text{b}\over \text{y} = \text{z}\over \text{c} —- (5)

From (4) and  (5)

\text{x}\over \text{a} = \text{b}\over \text{ y} = \text{z}\over \text{c}

(ii) If a, b, c, d are in continued proportion, then prove that (b – c)² + (c – a)² + (b – d)² = (a – d)².

Answer

\text{a}\over \text{b} = \text{b}\over \text{c} = \text{c}\over \text{d} = k

c = dk

b = ck = dk²

a = bk = dk³

LHS: (dk² – dk)² + (dk – dk³)² + (dk² – d)²

= d²k²(k – 1)² + d²k²(1 – k²)² + d²(k² – 1)²

= d²{k²(k – 1)² + k²(1 – k²)² + (k² – 1)²}

= d²{k²(k² – 2k + 1) + k²(k⁴- 2k² + 1) + (k⁴- 2k² + 1)}

= d²(k⁴- 2k³ + k² + k⁶ – 2k⁴ + k² + k⁴- 2k² + 1)

= d²(k⁶ – 2k³ + 1)

= d²k⁶ – 2d²k³ + d²

= (dk³)² – 2(dk²)(d) + d²

= (dk³ – d)² = (a – d)² RHS (Proved)


Question – 9

Answer any One Question:

(i) Prove that the front angle formed at the centre of a circle by an arc is the double of the angle formed by the same arc at any point on the circle.

Answer

Given: ∠AOB is the angle at the center of the circle with center O, and ∠ACB is the angle at any point on the circle formed by the circular arc APB.

Prove that the angle subtended by an arc of a circle at the center is double the angle

To Prove: ∠AOB = 2∠ACB

Construction: C, O are joined, and CO is extended up to the point D.

Proof:

In △AOC,

OA = OC in each case (radii of the same circle).

∴ ∠OCA = ∠OAC

Again, in each case, side CO of Δ AOC is extended up to point D.

Exterior ∠AOD = ∠OAC + ∠OCA = 2∠OCA — (I)

In ΔBOC

OB = OC in each case (radii of the same circle).

Again, since side CO of ΔBOC is extended up to point D:

∴ Exterior ∠BOD = ∠OCB + ∠OBC = 2 ∠OCB — (II)

∠AOD + ∠BOD = 2∠OCA + 2∠OCB

∴ ∠AOB = 2(∠OCA + ∠OCB) = 2∠ACB — (III)

∴ ∠AOB = 2∠ACB (Proved)

(ii) State and prove Pythagoras theorem.

Answer

Pythagoras Theorem: In any right-angled triangle, the area of the square drawn on the hypotenuse is equal to the sum of the areas of the squares drawn on the other two sides.

Proof of pythagoras Theorem

Given: ABC is a right-angled triangle whose ∠A is a right angle.

To prove: BC² = AB² + AC²

Construction: I draw a perpendicular AD on the hypotenuse BC from the right angular point A which intersects the side BC at the point D.

Proof: In right-angled Δ ABC, AD is perpendicular on the hypotenuse BC.

∴ Δ ABD and Δ CBA are similar.

Hence,

{\text{AB} \over \text{BC}} = {\text{BD} \over \text{AB}},

∴ AB² = BC × BD —- (i)

Again, ΔCAD and ΔCBA are similar.

Hence,

{\text{AC} \over \text{BC}} = {\text{DC} \over \text{AC}}

∴ AC² = BC × DC —- (ii)

So, by adding (i) and (ii), I get:

AB² + AC² = BC × BD + BC × DC.

= BC (BD + DC) = BC × BC = BC².

∴ BC² = AB² + AC² [proved]


Question – 10

Answer any One Question:

(i) In a triangle ABC, AB = AC and E is any point on the extended BC. If the circumcircle of ΔABC intersects AE at point D, prove that ∠ACD = ∠AEC.

Answer

In_a_triangle_ABC__AB___AC_and_E_is_any_point_on_the_extended_BC._If_the_circumcircle_of_ΔABC_intersects_AE_at_point_D__prove_that__ACD____AEC-removebg-preview

In △ABC, AB = AC,

∴ ∠ABC = ∠ACB ………..(1)

Now, ABCD is a cyclic quadrilateral,

∴ ∠ABC + ∠ADC = 180°

or, ∠ACB + ∠ADC = 180° ……..(2) [from (1)]

Again, ∠ACB + ∠ACE = 180° ……..(3)

From (2) and (3), we get:

∠ACB + ∠ADC = ∠ACB + ∠ACE

or, ∠ADC = ∠ACE

or ∠DCE + ∠DEC = ∠ACD + ∠DCE

or ∠DEC = ∠ACD

∴ ∠ACD = ∠DEC

Hence, ∠ACD = ∠AEC.

(ii) The two medians BE and CF of ΔABC intersect each other at the point G and if the line segment FE intersects the line segment AG at the point O, then prove that AO = 3OG.

Answer

The two medians BE and CF of ΔABC intersect each other at the point

Contruction: Extent AG to Point D.

G is the centroid of Δ ABC. AD is a median

Proof: AG : GD = 2 : 1

\text{AG}\over \text{GD} = 2\over 1

or, \text{AO + OG}\over \text{OD - OG} = 2\over 1

or, 2 OD – 2OG = OA + OG

or, 2 OD – OA =  3OG —– (i)

In Δ ABD, OF || BD

\text{AF}\over \text{BF} = \text{AO}\over \text{OD}

or, \text{AF}\over \text{AF} = \text{AO}\over \text{OD}

or, 1 = \text{AO}\over \text{OD}

or, OD = OA

Put OD = OA

2 OA – OA =  3OG

or, OA = 3OG (Proved)


Question – 11

Answer any One Question:

(i) Draw an isosceles triangle with one angle 120° and equal sides of length 4 cm, then draw its circumcircle.

Answer

Draw an isosceles triangle with one angle 120° and equal sides of length 4 cm, then draw its circumcircle.

(ii) Draw a circle of radius 2.8 cm length. Then draw two tangents of the circle from the point outside the circle and is at distance of 7.5 cm from the centre.

Answer

Draw a circle of radius 2.8 cm length. Then draw two tangents of the circle from the point outside the circle and is at distance of 7.5 cm from the centre.


Question – 12

Answer any Two Questions:

(i) If the sum of two angles is 135° and their difference is π/12, then determine the sexagesimal value and circular value of two angles.

Answer

A + B = 135º —- (1)

A – B = π/12 = 15º—- (2)

Adding (1) and (2)

(A + B) + (A – B) = 150º

or, 2A = 150º

or, A = 75º

Put A in equation (1)

A + B = 135º

or, 75º + B = 135º

or, B = 135º – 75º = 60º

In Degree, A = 75º and B = 60º

In Circular values, A = 5π/12 and B = π/3

(ii) If \text{sinθ}\over \text{x} = \text{cosθ}\over \text{y}, then show that sinθ – cosθ = \text{(x - y)}\over\text{√(x² + y²)}.

Answer

\text{sinθ}\over \text{x} = \text{cosθ}\over \text{y} = k

∴ sinθ = kx — (1)  and cosθ = ky — (2)

Squaring and adding (1) and (2)

(kx)² + (ky)² = sin²θ + cos²θ

or, k²(x² + y²) = 1

or, k = 1\over \sqrt{\text{x}^2+\text{y}^2}

sinθ = x\over \sqrt{\text{x}^2+\text{y}^2} and cosθ = y\over \sqrt{\text{x}^2+\text{y}^2}

∴ sinθ – cosθ = \text{x - y}\over \sqrt{\text{x}^2+\text{y}^2}

(iii) If x tan 30° + y cot 60° = 0 and 2x – y tan 45° = 1, then calculate the value of x and y.

Answer

x 1\over √3 + y 1\over √3 = 0

or, x + y = 0 — (1)

2x – y tan 45° = 1

or, 2x – y = 1 — (2)

Adding (1) and (2) we get

3x = 1 ⇒ x = 1\over 3

Substitutuing x in equation (1)

x + y = 0

or, 1\over 3+ y = 0

or, y = –1\over 3

∴ x = 1\over 3 and y = –1\over 3


Question – 13

Answer any One Question:

(i) A house of 15 m height stands on one side of a park and from a point on the roof of the house the angle of depression of the foot of the chimney of brick kiln of the other side is 30° and the angle of elevation of the top of the chimney of brick kiln is 60°. Calculate the height of the chimney and the distance between the brick kiln and the house.

Answer

A house of 15 m height stands on one side of a park and from a point on the roof of the house the angle of depression of

Height of House (AB) = 15 m

Total height of chimney (CE) = CD + DE

In Δ ABC,

tan 30° = AB/BC

or, 1/√3 = 15/BC

or, BC = 15√3 m

In fig, BC = AD = 15√3 m

In ΔADE,

tan 60° = DE/AD

or, √3 = DE/15√3

or, DE = 15√3 × √3 = 45 m

∴ Total height of the chimney = CD + DE

= 15 + 45  = 60 m (Ans)

(ii) From a point on the roof of a house of 11 meter height, it is observed that the angles of depression of the top and foot of lamp post are 30° and 60° respectively, calculate the height of the lamp post.

Answer

From a point on the roof of a house of 11 meter height it is observed that the angles of depression of the top

In ABC,

tan 60° = 11\over \text{y}

or, √3 = 11\over \text{y}

or, y = 11\over √3

In ADE,

tan 30° = \text{DE}\over \text{AD}

or, tan 30° = \text{11 - x}\over \text{y}

or, tan 30° =\text{11 - x}\over {11\over √3}

or, 1\over √3 = (11 - x)√3\over 11

or, 11 = (11 – x)√3 × √3

or, 33 – 3x = 11

or, 3x = 22

or, x = 22/3 = 7.33 m


Question – 14

Answer any One Question:

(i) The length of the radius of cross-section of a solid right circular rod is 3.2 cm. By melting the rod, 21 solid spheres are made. If the radius of the sphere is 8 cm, then determine the length of the rod.

Answer

Radius = 3.2 dcm = 32 cm

Length of rod = x cm (Let)

∴ the volume of the rod = π × (32)² × x

The radius of each sphere = 8 cm

∴ The volume of each sphere = 4\over 3 × π × 8³

So, the volume of 21 spheres = 21 × 4\over 3 × π × 8³

= 28 × 512π

ATP

π × (32)² × x = 28 × 512π

or, x = 28 × 512\over 32 × 32 = 14 cm

(ii) The quantity of iron sheet to make a body of right circular conical shape is 75 3\over7 m². If the slant height of it is 5 m, calculate the volume of the conical body and its height. Again determine the expenditure to colour the curved surface area of the buoy at the rate of ₹2.80 per m².

Answer

Slant height = 5 m

Radius of buoy = r  m

∴ TSA of a buoy = 22\over 7r(r+5)

or, 22\over 7r(r+5) = 75 3\over7

or, 22\over 7r(r+5) = 528\over7

or, r(r+5) = 528 × 7\over7 × 22

or, r² + 5r = 24

or, r² + 5r – 24 = 0

or, (r + 8)(r – 3) = 0

∴ r = 3 or -8

Height of the buoy (h) = \sqrt{5^2-3^2} = √16 = 4 cm

(a) Volume of buoy = {1\over 3}×{22\over 7} × 3 × 3 × 4

= 37 {5\over 7} cm³

(b) Cost of colouring = 2.80 × 528\over7 = ₹ 211.20


Question – 15

Answer any Two Question:

(i) Calculate the mean from the following data:

Class Frequency
0 – 30 12
30 – 60 15
60 – 90 20
90 – 120 25
120 – 150 8

Answer

Class Class mark (x) f fx
0 – 30 15 12 180
30 – 60 45 15 675
60 – 90 75 20 1500
90 – 120 105 25 2625
120 – 150 135 8 1080
Total ∑f = 80 ∑fx = 6060

Mean = ∑fx\over ∑f = 6060\over 80 = 75.75

The mean of the given data is 75.75.

(ii) Find the median of data  from the following frequency distribution table:

Marks obtained Number of student
Less than 10 8
Less than 20 15
Less than 30 29
Less than 40 42
Less than 50 60
Less than 60 70

Answer

Marks obtained Frequency (f)
CF
10 – 20 8 8
20 – 30 7 15
30 – 40 14 29
40 – 50 13 42
50 – 60 18 60
60 – 70 10 70

Median Class = N\over 2 = 70\over 2 = 35th Observation

∴ Median Class = 40 – 50

Median = 40 + {70\over 2}- 29\over 13 × 10

= 40 + 35- 29\over 13 × 10

= 40 + 4.615 = 44.615

(iii) Find the mode of data from the following frequency distribution table:

Class Interval Frequency
0 – 5 2
5 – 10 6
10 – 15 10
15 – 20 16
20 – 25 22
25 – 30 11
30 – 35 8
35 – 40 5

Answer

The modal class is 20 − 25 with fm = 22.

Given:

  • L = 20 (lower boundary of modal class)
  • fm = 22 (frequency of modal class)
  • f1 = (frequency of previous class)
  • f2 = (frequency of next class)
  • h = 5 (class width)

Mode = 20 + {22-16 \over 2 (22)-16-11} \times 5

= 20 + 1.7645 = 21.76

The mode of the given data is approximately 21.76.

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