# NCERT Solutions for Class 11 Economics Statistics for Economics Chapter 5

## Measures of Central Tendency Class 11

### Exercise : Solutions of Questions on Page Number : 71

Q1 :

Which average would be suitable in the following cases?

(ii) Average intelligence of students in a class.

(iii) Average production in a factory per shift.

(iv) Average wage in an industrial concern.

(v) When the sum of absolute deviations from average is least.

(vi) When quantities of the variable are in ratios.

(vii) In case of open-ended frequency distribution.

(i) The demand for the average size of any readymade garment is the maximum. As, the modal value represents the value with the highest frequency, so the number of the average size to be produced is given by the Modal value.

(ii) Median will be the best measure for calculating the average intelligence of students in a class. It is the value that divides the series into two equal parts. So, number of students below and above the average intelligence can easily be estimated by median.

(iii) It is advisable to use mean for calculating the average production in a factory per shift. The average production is best calculated by arithmetic mean.

(iv) Mean will be the most suitable measure. It is calculated by dividing the sum of wages of all the labour by the total number of labours in the industry.

(v) When the sum of absolute deviations from average is the least, then mean could be used to calculate the average. This is an important mathematical property of arithmetic mean. The algebraic sum of the deviations of a set of n values from A.M. is 0.

(vi) Median will be the most suitable measure in case the variables are in ratios. It is least affected by the extreme values.

(vii) In case of open ended frequency distribution, Median is the most suitable measure as it can be easily computed. Moreover, the median value can be estimated even in case of incomplete statistical series.

Q2 :

The most suitable average for qualitative measurement is

(a) arithmetic mean

(b) median

(c) mode

(d) geometric mean

(e) none of the above

Median is the most suitable average for qualitative measurement. This is because Median divides a series in two equal parts.

Q3 :

Which average is affected most by the presence of extreme items?

(a) median

(b) mode

(c) arithmetic mean

(d) none of the above

Q4 :

The algebraic sum of deviation of a set of n values from A.M. is

(a) n

(b) 0

(c) 1

(d) none of the above

Q5 :

Comment whether the following statements are true or false.

(i) The sum of deviation of items from median is zero.

(ii) An average alone is not enough to compare series.

(iii) Arithmetic mean is a positional value.

(iv) Upper quartile is the lowest value of top 25% of items.

(v) Median is unduly affected by extreme observations.

Q6 :

If the arithmetic mean of the data given below is 28, find (a) the missing frequency, and (b) the median of the series:

 Profit per retail shop (in Rs) 0 - 10 10 - 20 20 - 30 30 - 40 40 - 50

Q7 :

The following table gives the daily income of ten workers in a factory. Find the arithmetic mean.

 Workers A B C D E

Q8 :

Following information pertains to the daily income of 150 families. Calculate the arithmetic mean.

 Income (in Rs) Number of families More than 75 150

Q9 :

The size of land holdings of 380 families in a village is given below. Find the median size of land holdings.

 Size of Land Holdings (in acres) Less than 100 100 - 200 200 - 300 300 - 400

Q10 :

The following series relates to the daily income of workers employed in a firm. Compute (a) highest income of lowest 50% workers (b) minimum income earned by the top 25% workers and (c) maximum income earned by lowest 25% workers.

 Daily Income (in Rs) 10 - 14 15 - 19 20 - 24 25 - 29

Q11 :

The following table gives production yield in kg. per hectare of wheat of 150 farms in a village. Calculate the mean, median and mode values.

 Production yield (kg. per hectare) 50 - 53 53 - 56 56 - 59 59 - 62 62 - 65