The mean monthly salary paid to 77 employees in a company was Rs. 78. The mean salary of 32 of then was Rs. 45 and of the other 25 was Rs. 82. What was the mean salary of the remaining ?

Explanation

`"Given: "N=77,barX_(123)=78" "N_(1)=32,barX_(1)=45`
`N_(2)=25,barX_(2)=82" "N_(3)=77-32-25=20`
Using the formula of combined arithmetic mean, we have
`barX_(123)=(barX_(1)N_(1)+barX_(2)N_(2)+barX_(3)N_(3))/(N_(1)+N_(2)+N_(3))`
`78=(45xx32+82xx25+barX_(3)xx20)/77`
`78=(1,440+2,050+20barX_(3))/77`
`78=(3,490+20barX_(3))/77`
`3,490+20barX_(3)=6,006`
`20barX_(3)=6,006-3,490`
`20barX_(3)=2,516`
`barX_(3)=(2,516)/20=125.8`
Mean salary of the remaining employees = Rs `125.8`.