Question

The length of 40 leaves of a plant are measured correct to the nearest milli-metre and the date obtained is represented in the following table:

Find the median length of the leaves.

Answer 1

We have n = 40

So, n/2 = 40/2 = 20

The cumulative Frequency just greater than  is 29 then the median class is 144.5 – 153.5 such that

the lower limit (l) = 144.5

cumulative frequency of the class preceding 144.5 – 153.5 (cf) = 17

frequency of the median class 144.5 – 153.5 = 12,

class size (h) = 9

Using the formula,

= 144.5 + 2.25

= 146.75

So, the median length of the leaves is 146.75 mm.