Question

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.

Answer 1

Given, the number of girls out of 50 students = 30

∴ The number of boys out of 50 students = 50 – 30 = 20

Now, the marks obtained by 30 girls = 30 × 73 = 2190 and the marks obtained by 20 boys = 20 × 71 = 1420  ...[Mean of marks scored by girls in a test is 73 and that of boys is 71]

∴ Mean score of the whole class

= `("Marks obtained by 30 girls" + "Marks obtained by 20 girls")/("Number of girls" + "Number of boys")`

= `(2190 + 1420)/(20 + 30)`

= `3610/50`

= 72.2

Hence, the mean score of whole class is 72.2.