Question

the mean of 20 observations is -100. the first observation is increased by 2, second by 6, third by 12 and so on. the new mean is

Answer 1

Answer:

149

Step-by-step explanation:

Step-by-step explanation:

mean of 20 observation = - 100

sum of observation /no of observation = - 100

sum of all the observation = - 100 ×20

sum of all observation = - 2000

Increase in observation =

1 = 2×1=2

2 = 3 x 2 = 6

3 = 4 x 3 = 12

4 = 5 x 4 = 20

5 = 6 x 5 = 30

6 = 7 x 6 = 42

and so on..

7 = 56, 8 = 72, 9 = 90, 10= 110, 11= 132, 12=156, 13=182, 14=210, 15=240, 16 = 272, 17 = 306, 18 = 342, 19 = 380, 20 = 420.

Sum of all of above increase = 2 + 6 + 12 + .....+420 = 3080

So new sum = -100 + 3080 = 2980

New Mean = new sum of all observation /no of observation = 2980 / 20 = 149

Answer 2

Answer:

48.3

Step-by-step explanation:

Given The mean of 20 observations is -100. the first observation is increased by 2, second by 6, third by 12 and so on. the new mean is

So we get the numbers after increasing as

- 98, - 94, - 88, - 80, - 70, - 58, - 44, - 28, - 10, 8, 28, 52, 76, 102, 130, 160, 192, 226, 262, 300

Adding all the numbers we get 966 and dividing by 20 we get 966/20 = 48.3

So mean will be 48.3.