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Question

Consider the following grouped frequency distribution :

Class0-1010-2020-3030-4040-5050-60
Frequency124643

What is the mean deviation about the mean ?

This question was previously asked in
NDA I 2022 GAT Previous Year Paper (10-Apr-2022)
The correct answer is

10.65

Using class midpoints \(5,15,25,35,45,55\) and frequencies \(1,2,4,6,4,3\), \(N=20,\ \sum f_ix_i=690\) and \(\bar{x}=34.5\).

The weighted absolute deviations are \(29.5,39,38,3,42,61.5\), totalling \(213\). Hence the midpoint-based mean deviation about the mean is \(\frac{\sum f_i|x_i-34.5|}{20}=\frac{213}{20}=10.65\).

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Similar Questions

  1. The sum of deviations of n number of observations measured from 2.5 is 50. The sum of deviations of the same set of observations measured from 3.5 is -50. What is the value of n?

  2. What is the coefficient of mean deviation of 21, 34, 23, 39, 26, 37, 40, 20, 33, 27 (taken from mean)?

  3. What is the mean deviation of the first 10 natural numbers?
  4. What is the mean deviation from the mean of the numbers 10, 9, 21, 16, 24 ?

  5. What is the mean deviation of first 10 even natural numbers?


Important Questions from Mean Deviation

  1. If the mean deviation of a set of observations is 15, then the value of quartile deviation is:  

  2. If the number of observations in a series is 15, then the third quartile is equal to:

  3. Let xi, i = 1, 2, ..., n be n observations and wi = pxi + k, i = 1, 2, ..., n where p and k are constants. If the mean of xi's is 48 and standard deviation is 12, whereas the mean of wi's is 55 and standard deviation is 15, then the value of p and k should be

  4. If the mean deviation 1, 1 + d, 1 + 2d, ..., 1 + 100d from their mean is 255, then d is equal to

  5. The mean of 5 observation is 5 and their variance is 124. If three of the observations are 1, 2, 6, then the mean deviation from the mean of the data is

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