# 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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