Skip to content
ICSEClass XMathematicsMeasures Of Central Tendency03 Mark2026 Easy

QQuestion

Find the mean of the following frequency distribution using step-deviation method.
Take assumed mean = 28.

Class interval Frequency
0–8 10
8–16 20
16–24 14
24–32 16
32–40 18
40–48 22

Exam-ready answer • 03 Mark

Answer

Here, class size i = 8 and assumed mean A = 28.

Class interval f x d = x − A t = d/i ft
0–8 10 4 −24 −3 −30
8–16 20 12 −16 −2 −40
16–24 14 20 −8 −1 −14
24–32 16 28 0 0 0
32–40 18 36 8 1 18
40–48 22 44 16 2 44
Total Σf = 100 Σft = −22

Mean = A + \left(\frac{\sum \mathrm{ft}}{\sum \mathrm{f}}\right)\times \mathrm{i}

= 28 + \left(\frac{-22}{100}\right)\times8

= 28 + 8(-0.22)

= 28 – 1.76

= 26.24

Was this answer helpful?

Related Questions

More ICSE Easy level questions

1/12

Rakhi’s mobile number has the following integers : 1, 6, 9, 8, 9, 1, 7, 8, 9 The mode of the above given data is : (a) 1 (b) 6 (c) 8 (d) 9

Easy 01 Mark

Using a graph paper, draw an ogive for the following distribution which shows a record of weight in kilograms of 100 students. Weight (in kg) Number of students 35–40 4 40–45 6 45–50 10 50–55 24 55–60 26 60–65 17 65–70 8 70–75 5 Use your ogive to estimate the following: (a) the median weight of the students. (b) percentage of students whose weight is 60 kg or more. (c) the weight above which 20% of the students lie.

Easy 06 Mark

The following table gives the marks scored by a set of students in an examination. Calculate the mean of the distribution using the shortcut method. Marks Number of students (f) 0–10 3 10–20 8 20–30 14 30–40 9 40–50 4 50–60 2

Easy 03 Mark

The following distribution gives the daily wages of 60 workers of a factory: Daily income (₹) Number of workers 200–300 6 300–400 10 400–500 14 500–600 16 600–700 10 700–800 4 Use graph paper. Take 2 cm = ₹100 along one axis and 2 cm = 2 workers along the other axis. Draw a histogram and hence find the mode of the distribution.

Easy 03 Mark

The histogram drawn on the graph represents the number of students of different heights (in cm). Using the graph, answer the following: (a) the number of students whose height is 150 cm and above. (b) the modal height. (c) the total number of students.

Moderate 03 Mark

Which of the following cannot be determined graphically for a grouped frequency distribution? (a) Median (b) Mode (c) Quartiles (d) Mean

Easy 01 Mark

Assertion (A): The mean of the first 9 natural numbers is 4.5. Reason (R): Mean = (a) A is true, R is false. (b) A is false, R is true. (c) Both A and R are true, and R is the correct reason for A. (d) Both A and R are true, and R is not the correct reason for A.

Easy 01 Mark

The following observations are arranged in ascending order: 27, 31, 46, 52, x, x + 4, 71, 79, 85, 90 If the median is 64, then the value of x is: (a) 60 (b) 61 (c) 62 (d) 66

Easy 01 Mark

Use graph paper to answer this question. During a medical check-up of 60 students in a school, their weights were recorded as follows: Weight (kg) Number of students 28–30 2 30–32 4 32–34 10 34–36 13 36–38 15 38–40 9 40–42 5 42–44 2 Taking 2 cm = 2 kg along one axis and 2 cm = 10 students along the other axis, draw an ogive. Use the graph to find: (a) the median (b) the upper quartile (c) the number of students whose weight is above 37 kg.

Easy 06 Mark

For the following frequency distribution, find: (a) the mean, to the nearest whole number. (b) the median. x 10 11 12 13 14 15 16 f 3 2 2 6 3 5 3

Moderate 03 Mark

The following table gives the duration of movies in minutes: Duration (minutes) Number of movies 100–110 5 110–120 10 120–130 17 130–140 8 140–150 6 150–160 4 Using the step-deviation method, find the mean duration of the movies.

Moderate 03 Mark

A life insurance agent found the following distribution of ages of 100 policy holders: Age (years) Frequency Cumulative frequency 20–25 2 2 25–30 4 6 30–35 12 18 35–40 20 38 40–45 28 66 45–50 22 88 50–55 8 96 55–60 4 100 On a graph sheet, draw an ogive using the given data. Take 2 cm = 5 years along one axis and 2 cm = 10 policy holders along the other axis. Use your graph to find: (a) the median age. (b) the number of policy holders whose age is above 52 years.

Moderate 04 Mark