Question

the mean of 7 number is 42 if one number is excluded then the mean is 39 find the excluded number ​

Answer 1

X1 +X2+ X3+.....+X7 = 42×7 =294....(1)

If one no. is exclude then,

X1+X2 + X3+ X4 ....+ X6 = 39×6 =234..(2)

equation (1) - (2)

X7 = 294 -234= 60