A class consists of 50 students out of which 30 are girls. The mean of marks scored by girls in a test is 73 (out of 100) and that of boys is 71. Determine the mean score of the whole class.
Solution:
Given, a class consists of 50 students out of which 30 are girls.
The mean marks scored by girls in a test is 73 out of 100
The mean marks scored by boys in a test is 71 out of 100
We have to determine the mean score of the whole class.
Mean = sum of all observations / total number of observations
Number of girls = 30
Number of boys = 50 - 30 = 20
Mean score of girls = sum of marks of all girls / number of girls
73 = sum of marks of all girls / 30
sum of marks of all girls = 73(30) = 2190
Mean score of boys = sum of marks of all boys / number of boys
71 = sum of marks of all boys / 20
sum of marks of all boys = 71(20) = 1420
Mean of whole class = (sum of marks of all girls + sum of marks of all boys) / (number of girls + number of boys)
= (2190 + 1420) / (30 + 20)
= 3610/50
= 361/5
= 72.2
Therefore, the mean of the whole class is 72.2
✦ Try This: A coin is tossed twice. Find the probability of getting exactly one head.
☛ Also Check: NCERT Solutions for Class 9 Maths Chapter 14
NCERT Exemplar Class 9 Maths Exercise 14.3 Problem 11
A class consists of 50 students out of which 30 are girls. The mean of marks scored by girls in a test is 73 (out of 100) and that of boys is 71. Determine the mean score of the whole class.
Summary:
A class consists of 50 students out of which 30 are girls. The mean of marks scored by girls in a test is 73 (out of 100) and that of boys is 71. The mean score of the whole class is 72.2
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