 # R S Aggarwal Solutions for Class 11 Maths Chapter 30 Statistics Exercise 30B

Class 11 Chapter 30 – Statistics exercise 30B solutions are provided here. All solutions have been prepared by our experts and they have provided accurate answers to all the exercise questions. This exercise introduces students to a lot of questions related to variance and standard deviation of a discrete frequency distribution.

Variance and standard deviation Formulas: ## Download PDF of R S Aggarwal Solutions for Class 11 Maths Chapter 30 Statistics Exercise 30B        ### Access Answers to Maths R S Aggarwal Class 11 Chapter 30 Statistics Exercise 30B Page number 935

Question 1: Find the mean, variance and standard deviation for the numbers 4, 6, 10, 12, 7, 8, 13, 12.

Solution:

Given data: 4, 6, 10, 12, 7, 8, 13, 12

Sum of observations = 4 + 6 + 10 + 12 + 7 + 8 + 13 + 12 = 72

Total number of observation = 8

Find Mean:

Mean = (Sum of observations) / (Total number of observation)

= 72/8 = 9

Mean = 9

Find Variance: Find Standard Deviation: Question 2: Find the mean, variance and standard deviation for first six odd natural numbers.

Solution:

Given data: First six odd natural numbers = 1, 3, 5, 7, 9, 11

Sum of observations = 1 + 3 + 5 + 7 + 9 + 11 = 36

Total number of observation = 6

Find Mean:

Mean = (Sum of observations) / (Total number of observation)

= 36/6 = 6

Mean = 6

Find Variance: Find Standard Deviation: Question 3: Using short cut method, find the mean, variance and standard deviation for the data :

 xi 4 8 11 17 20 24 32 fi 3 5 9 5 4 3 1

Solution: Mean: Variance: Standard deviation Question 4: Using short cut method, find the mean, variance and standard deviation for the data :

 xi 6 10 14 18 24 28 30 fi 2 4 7 12 8 4 3

Solution: Mean: Variance: Standard deviation: Question 5: Using short cut method, find the mean, variance and standard deviation for the data :

 xi 10 15 18 20 25 fi 3 2 5 8 2

Solution: Mean: Variance: Standard deviation: Question 6: Using short cut method, find the mean, variance and standard deviation for the data :

 xi 92 93 97 98 102 104 109 fi 3 2 3 2 6 3 3

Solution: Mean: Variance: Standard deviation: ## R S Aggarwal Solutions for Class 11 Maths Chapter 30 Exercise 30B

Class 11 Maths Chapter 30 Statistics Exercise 30B is based on the following topics:

• Variance
• Standard deviation
• Variance and standard deviation of a discrete frequency distribution