Question

The mean of 15 no is 8 if 3 is added to every no find the new mean

Answer 1

mean=sum of number /total number
8=sum of numbers/15

sum of numbers=8 x 15=120

now, according to question,
add 3 all numbers
hence ,
sum of 15 numbers+3 x 15=120+45=165
now . sum of total numbers =165

hence,
mean=165/15=11

Answer 2

Mean= Sum of observations/ Total number of observations

8=sum of observations/15

sum of observations=8 x 15=120

A/Q,
 sum of 15 observations + 3 x 15= 120 + 45=165

 sum of total observations =165

Mean=165/15=11

Hence, the new mean is 11