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.

Explanation

Given, the number of girls out of 50 students=30
`therefore` The numberof boys out of 50 students= 50-30=20
Now, the marks obtained by 30 girls =`30 xx 73=2190`
and the marks obtained by 20 boys `=20 xx 71=1420`
[`therefore` mean of marks scored by girls in a test is 73 and that of boys is 71]
`therefore` Mean score of the whole class
`=("Marks obtained by 30 girls + Marks obtained by 20 girls")/(50)/("Number of girls+ Number of boys")`
`(2190+1420)/(20+30)=3610/50=72.2`
Hence, the mean score of whole class is 72.2.