Question

Let the mean and the variance of 5 observations x 1, x 2, x 3, x 4, x 5 be $\frac{24}{5}$ and $\frac{194}{25}$, respectively. If the mean and variance of the first 4 observations are $\frac{7}{2}$ and a, respectively, then (4 a + x 5) is equal to

• A. 13
• B. 15
• C. 17
• D. 18

Answer 1

Answer: (B)

15

Answer 2

The correct option is(B): 15

$\sum_i=1^5x_i=24....(i)$

$\sum{x^2_i=1154}....(i)$

⇒ x 5 = 10

⇒ x 5 + 4 a = 10 + 5 = 15