799
Q:

A problem is given to three students whose chances of solving it are 1/2, 1/3 and 1/4 respectively. What is the probability that the problem will be solved?

 A) 1/4 B) 1/2 C) 3/4 D) 7/12

Explanation:

Let A, B, C be the respective events of solving the problem and  be the respective events of not solving the problem. Then A, B, C are independent event

are independent events

Now,  P(A) = 1/2 , P(B) = 1/3 and P(C)=1/4

$∴$ P( none  solves the problem) = P(not A) and (not B) and (not C)

= $PA∩B∩C$

= $PAPBPC$

=  $12×23×34$

= $14$

Hence, P(the problem will be solved) = 1 - P(none solves the problem)

= $1-14$= 3/4

Q:

A sequence , has odd number of terms. Then the median is

 A) axn2+1 B) axn2-1 C) axn-1 D) axn2

Explanation:

0 180
Q:

The mean of a distribution is 15 and the standard deviation is 5. What is the value of the coefficient variation?

 A) 16.66% B) 66.66% C) 33.33% D) 100%

Explanation:

2 252
Q:

If the standard deviation of a population is 3, what would be the population variance?

 A) 9 B) 6 C) 8 D) 15

Explanation:

0 939
Q:

The variance of a set of data is 169. Then the standard deviation of the data is

 A) +-13 B) 13 C) 69 D) 84.5

Explanation:

1 933
Q:

If the standard deviation of a population is 10, what would be the population variance?

 A) 100 B) 30 C) 5 D) 20

Explanation:

1 326
Q:

The mean of 20 observations is 19. One more observation is included and the new mean becomes 20. The 21st observation is

 A) 20 B) 30 C) 40 D) 42

Explanation:

2 360
Q:

The mean of a distribution is 18 and the standard deviation is 4.5. What is the value of the coefficient of variation?

 A) 50% B) 25% C) 100% D) 75%

Explanation:

0 360
Q:

The mean of the data 2, 9, 9, 3, 6, 9, 4 is

 A) 33/7 B) 6 C) 43/7 D) 7