Important Questions for Class 9 Chapter 14 – Statistics

The set of important questions provided will help you in doing a complete revision in Maths and getting good scores. Hurry up! Download your free PDF now!

Important questions based on NCERT syllabus for Chapter 14 - Statistics:

Question 1: The above table depicts the age group of people living in an apartment. Since the group width is unequal find the length of rectangle with respect to age group width 5 per interval. Solution: Question 2: The mean weight of a group of seven boys is 56 kgs. The individual weights (in kg) of six of them are 52, 57, 55, 60, 59 and 55. Find the weight of the seventh boy.
Solution:
Mean weight of 7 boys = 56 kg.
Total weight of 7 boys = (56×7) kg = 392 kg
Total weight of 6 boys = (52 + 57 + 55 + 60 + 59 + 55) kg
= 338 kg
Weight of the 7th boy = (total weight of 7 boys) - (total weight of 6 boys)
= (392 - 338) kg = 54 kg
Hence, the weight of the seventh boy is 54 kg.

Question 3: The mean of 25 observations is 36. If the mean of the first 13 observations is 32 and that of the last 13 observations is 39, find the 13th observation.
Solution:
Mean of the first 13 observations = 32
Sum of the first 13 observations = (32×13) = 416
Mean of the last 13 observations = 39
Sum of the last 13 observations = (39×13) = 507
Mean of 25 observations = 36
Sum of all the 25 observations = (36×25) = 900
∴ The 13th observation = (416 + 507 - 900) = 23
Hence, the 13th observation is 23.