Question

A random sample of 30 malls shows the number of stores each other one contains. find the mean and modal class

Class boundaries            Frequency

11-15                                  7

16-20                                  4

21-25                                 6

26-30                                10

31-35                                 3

Answer 1

Answer :

given data :-

A random sample of malls = 30

n = 30

we have a data of Class boundaries and Frequency

now we find out the mean and modal class

now we construct the tabular form

that is,

	Class boundaries (X)	Frequency (F)	(X*F)
1	11-15 => 26/2=13	7	13*7=91
2	16-20 => 36/2=18	4	18*4=72
3	21-25 => 46/2=23	6	23*6=138
4	26-30 => 56/2=28	10	28*10=280
5	31-35 => 66/2=33	3	33*3=99
TOTAL		30	680

Now we need to find out the mean

we know that,

mean = XF/N

= 680/30

= 22.666

The mean is = 22.666

now we need to find out the modal class

that is,

Modal class = Class with maximum frequency

= 26-30

= (26+30)2

= 56/2

= 28

the modal class is = 28