Question

the mean of 15 numbers is 8. if 2is added to every no. what will be the new mean

Answer 1

mean= 8
Total number of observations= 15

mean = sum of the observations/ number of the observations

8= sum of the observations / 15
sum of the observations = 8×15
= 120

now, 2 is added to every number.
then, 2×15 = 30 is added,

then the new sum = 120 + 30

= 150

New mean = New sum of observation/number of observation

⇒ 150/15

New mean = 10

Answer 2

Given,  there are 15 numbers

Mean = 8.Let their sum be x.

So mean = x/15 =8.

If two is added to each number then the  sum increases by 15*2 = 30.So, for finding the new mean we'll divide it  by 15

∴ Mean = (x+30)/15⇒ 8+2 =10.