Question

solve the question and show the solution
Find the mean of 25 observations if the mean of 15 of them is 18 and that if remaining ones is 13

Answer 1

Multiply 15 with 18=370
and then multiply 13 with 10=130
add them 130 + 370 = 500
so the mean will be 500/25=20

Answer 2

here is the solution to this problem....