Question

if the mean of 6 observations x, x+3, x+6,x+9,x+12 and x+15 is 18, find the mean of the first four observations.with explaination​

Answer 1

Answer:

15

Step-by-step explanation:

mean = 19

sum of 6 observations ÷ 6 =18

(x+x+3+x+6+x+9+x+12 +x+15 )÷6= 18

6x + 45 = 18 ×6

6x = 108 - 45

6x = 63

x = 10.5

Therefore, The first four observations x, x+3, x+6,x+9 are 10.5, 13.5, 16.5, 19.5 respectively

mean = (10.5 + 13.5 + 16.5 + 19.5 ) ÷ 4

=60 ÷ 4

= 15