Chapter 17 Measures of Central Tendency Ex 17.7

Rajasthan Board RBSE Class 10 Maths Chapter 17 Measures of Central Tendency Ex 17.7

Question 1.
Marks obtained by 100 students are given in the following table.

Find their median.
Solution :
Preparing cumulative frequency table :

Here  = 50
Cumulative frequency just above 50 is 70 whose corresponding class-interval is 40 – 50.
Thus, median class =40 – 50
∵ l = 40, f = 44, C = 26, h = 10

Question 2.
Marks obtained by students of a class are given in the following frequency distribution :

Find their median.
Solution :
Preparing cumulative frequency table :

Here  =  = 50
Cumulative frequency just above 50 is 74 whose corresponding class-interval is 20 – 30.
Thus, median class =20 – 30
∵ l = 20, f = 42, C = 32, h = 10

= 20 +  = 20 + 4.29 = 24.29
Thus, median class = 24.29

Find median from the following frequency distribution (Q.3 and 4)
Question 3.

Solution :

Here  =  = 50
Cumulative frequency just above 50 is 65 whose corresponding class-interval is 40 – 50.
Thus, median class =40 – 50
∵ l = 40, f = 30, C = 35, h = 10

= 40 +  = 40 + 5 = 45
Thus, required median = 45

Question 4.

Solution :

Here  =  = 78.5
Cumulative frequency just above 78.5 is 122 whose corresponding class-interval is 16 – 24.
Thus, median class =16 – 24
∵ l = 16, f = 50, C = 72, h = 8

= 16 +  = 16 + 1.04 = 17.04
Thus, median class = 17.04