The mean of the five observations x, x + 2, x + 4, x + 6, x + 8 is 11.

The mean of the five observations x, x + 2, x + 4, x + 6, x + 8 is 11. Then the mean of the first three observations is
(a) 12
(b) 2
(c) 20
(d) 9

Anurag Mishra Professor Asked on 23rd February 2016 in Maths.
Add Comment
1 Answer(s)
Best answer

Answer: (d) 9 

Solution:-
The mean of five observation x, x + 2, x + 4, x + 6, x + 8 is 11.
Then, (x + x + 2 + x + 4 + x + 6 + x + 8)/5 = 11
(5 x + 20) = 11 x 5
5 x = 55 – 20
5 x = 35
x = 35/5
x =  7

Then, the value of first three observations x = 7, x + 2 = 7 + 2 = 9, x + 4 = 7 + 4= 11
So, mean of first three observations = (7 + 9 + 11)/3
= 27/3
= 9

Hence, the correct answer is option (d) 9.

Anurag Mishra Professor Answered on 25th February 2016.
Add Comment

Your Answer

By posting your answer, you agree to the privacy policy and terms of service.