Question

If the mean of 5 observations x +1,x + 2, x + 3 , x + 4 and x + 5 is 15 then what is the mean of the first 3 observations?

• A. 14
• B. 15
• C. 16
• D. 10

Answer 1

Answer:

A. 14

mean of 5 observations x +1,x + 2, x + 3 , x + 4 and x + 5 is 15 ⇒ { x +1 + x + 2 + x + 3 + x + 4 + x + 5} /5 = 15 5x + 15 = 75 5x = 60 x = 60/5 = 12 mean of the first 3 observations = { 13 + 14 +15 }/3 = 42/3 = 14