Question

4. The mean of eight numbers is 7. One more number is added and the mean is still 7. Find the number that has been added ​

Answer 1

Answer:

Mean =X = 27

No of observations = 7

Sum of observations = = 27 x 7 = 189

Let the included number be x

New Mean X' = 28

New number of observations 8

New sum of observations = 28 x 8

= 224 which is

Thus x=

equal to 189+x

224-189 = 35

Answer 2

Answer:

7 = sum of all numbers / 8

sum of all numbers = 7 × 8

= 56

sum of all numbers = 56 + x

numbers of numbers = 8 + 1 = 9

mean = sum of all numbers / numbers of numbers

=} 7 = 56+x/9

=} 56 + x = 7×9

=} 56 + x = 63

=} x = 63 - 56

=} x = 7 [ans)