(Q15) A student noted the number of cars passing through a spot on a road for 100 periods, each of 3 minutes, and summarised this in the table given below.

Number of cars	0-10	10-20	20-30	30-40	40-50	50-60	60-70	70-80
Frequency	7	14	13	12	20	11	15	8

Find the mode of the data.

Answer :

Number of cars	Frequency
0-10	7
10-20	14
20-30	13
30-40	12
40-50	20
50-60	11
60-70	15
70-80	8

Since the maximum frequency is 20, the modal class is 40-50

Lower boundary of the modal class 'l' = 40

Frequency of the modal class, f₁ = 20

Frequency of the class preceding the modal class, f₀ = 12

Frequency of the class succeeding the modal class, f₂ = 11

Height of the class, h = 10