Moderate 784 likes
Share

Question

If the arithmetic mean and total frequency of the following distribution are 50 and 120 respectively, then find the value of f1 and f2:

Class Frequency
0 – 20 17
20 – 40 f1
40 – 60 32
60 – 80 f2
80 – 100 19
WBBSE Class X Mathematics Statistics 04 Mark 2023

Answer

Class x f fx
0 – 20 10 17 170
20 – 40 30 f1 30f1
40 – 60 50 32 1600
60 – 80 70 f2 70f2
80 – 100 90 19 1710
Total 68 + f1 + f2 3480 + 30f1 + 70f2

Σf = 120

or, 68 + f1 + f2 = 120

or, f1 + f2 = 120 – 68

or, f1 + f2 = 52 — (1)

Σfx = mean × Σf

or, 3480 + 30f1 + 70f2 = 50 × 120

or, 30f1 + 70f2 = 2520

or, 3f1 + 7f2 = 252 — (2)

Solving (1) and (2), we get

f1 = 28

and  f2 = 24

Hence, the values of f1 and f2 are 28 and 24.

Related Questions

More WBBSE Moderate level questions

1/12
Moderate
Q. How can the given conversion be carried out?
A. The given conversion of ethene (H₂C = CH₂) to ethane (H₃C –...
View Question
Moderate
Q. State the resistance of 220 V – 100 W bulb
A. Power (P) = Resistance (R) = = = = 484 Ω
View Question
Moderate
Q. For which value of the angle of incidence in refraction of light is Snell’s law...
A. Snell’s law is not applicable when the angle of incidence is 0°.
View Question
Moderate
Q. Write whether the following statement is true or false: If coefficient of linear expansion of...
A. True Explanation: Coefficient of cubical expansion γ = 3 × coefficient of...
View Question
Moderate
Q. What is the number of molecules present in 16 g of O₂ at S.T.P.?
A. 3.011 × 10²³ Explanation: Given mass = 16 g Molecular mass =...
View Question
Moderate
Q. Write whether the following statement is true or false: According to Charles’ law, at (–)...
A. False Explanation: Charles' law states volume becomes zero at absolute zero (-273°C),...
View Question
Moderate
Q. Write the name of monomer of a polymer which is used to prepare non-stick utensils.
A. Tetra fluoro ethylene Explanation: Polytetrafluoroethylene (PTFE or Teflon) is used for non-stick...
View Question
Moderate
Q. Write down the IUPAC name of the following organic compound
A. 2-Bromopropane or (1) CH₃–CH₂–CH₂–OH → Propane-1-ol(2) CH₃–CH(OH)–CH₃ → Propane-2-ol
View Question
Moderate
Q. Name the metal which is extracted in thermite process.
A. Fe Explanation: Thermite process reduces metal oxides using Al at high temperature...
View Question
Moderate
Q. Fill up the blank: CaC₂ + N₂ → ____ + C
A. CaNCN / CaCN₂ (Calcium cyanamide) Explanation: Haber's process uses Fe as catalyst...
View Question
Moderate
Q. What happens when an iron spoon is dipped into acidified copper sulphate solution?
A. When an iron spoon is dipped into acidified copper sulphate solution, a...
View Question
Moderate
Q. Left Column 2.2.1 Metal present in German silver 2.2.2 A transuranium element 2.2.3 The metal...
A. 2.2.1 – (d), 2.2.2 – (c), 2.2.3 – (b), 2.2.4 – (a).​...
View Question