Question

Find the sum of the lower limit of the median class and the upper limit of the modal class :

Classes	10-20	20 -30	30-40	40 - 50	50-60	60-70
Frequency	1	3	5	9	7	3

Answer 1

Class	Frequency (f)	Cumulative frequency (c.f.)
10-20	1	1
20-30	3	4
30-40	5	9
40-50	9	18
50-60	7	25
60-70	3	28

Median = \(\frac N 2\)th term

\(= \frac{28}2\)

= 14th term

∴ Median class = 40-50

So the lower limit of the median class = 40

Modal class is the class interval with the highest frequency in the frequency table.

Therefore we have, maximum frequency = 9

So, modal class = 40-50

then the upper limit = 50

The sum of lower limit of the median class + the upper limit of the modal class

= 40 + 50 

= 90

Hence, 90 is the sum of lower limit of the median class and the upper limit of the modal class.

Answer 2

Their sum = 40 + 50 = 90