1145
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:

X attempts 100 questions and gets 340 marks. If for every correct answer is 4 marks and wrong answer is negative one mark, then the number of questions wrongly answered by Mr. X is:

 A) 14 B) 15 C) 12 D) 13

Explanation:

24 2425
Q:

If the standard deviation of 0, 1, 2, 3 ......... 9 is K, then the standard deviation of 10, 11, 12, 13 ........... 19 will be:

 A) K+1 B) K C) K+4 D) K+8

Explanation:

7 2247
Q:

The standard deviation of the set {10, 11, 12, 9, 8} is

 A) 1 B) √2 C) 2 D) 2√2

Explanation:

11 2034
Q:

Find the range of the data 2, 1, 2, 3, 5, 4, 7, 3, 5, 2, 4.

 A) 5 B) 4 C) 3 D) 6

Explanation:

4 2119
Q:

Find the median, mode and mean of 9, 5, 8, 9, 9, 7, 8, 9, 8.

 A) 9, 9, 9 B) 9, 8, 9 C) 8, 9, 8 D) 8, 9, 9

Explanation:

10 1844
Q:

In the usual set notation,  =

 A) A∪B∪A∪C B) A∩B∪A∩C C) A∪B∩A∪C D) A∪B∩A∩C

Explanation:

5 5432
Q:

Find the range and mode of the data 17, 18, 28, 19, 16, 18, 17, 29, 18

 A) 12 and 18 B) 13 and 18 C) 12 and 17 D) 11 and 17

Explanation:

5 1919
Q:

Find the standard deviation of {11, 7, 10,13, 9}

 A) 1 B) 2 C) 4 D) 5