Question

Mean of 100 observations is found to be 40. If at the time of computation two items are wrongly taken as 30 and 27 instead of 3 and 72, find the correct mean.

Answer 1

Given: `N = 100, barX = 40 `
`barX = (sumX)/N`
Or,`" "40 = (sumX)/100`
`:." "sumX("Wrong") = 40xx 100 = 4,000`
Correct values = 3 + 72 = 75
Incorrect values = 30 + 27 = 57
`"Correct "barX=(sumX"(Wrong)+(Correct Value)-(Incorrect Value)")/N`
` = (4,000+75-57)/100=(4,018)/100=40.18`
Corrected Mean = `40.18`.