- A basket contains 8 Blue and 10 Brown balls. There is another basket which contains 6 Blue and 8 Brown balls. One ball is to drawn from either of the two baskets. What is the probability of drawing a Blue ball?
55/12655/6337/12646/63NoneOption A

Solution:

P(choosing 1 basket)=1/2

P(Blue ball from 1st basket)=1/2*8C1/18C1=4/18

P(Blue ball from 2nd basket)=1/2*6C1/14C1=3/14

P=4/18+3/14=55/126.

- One card is drawn at random from a pack of 52 cards. What is the probability that the card drawn is either a black card or a queen?
7/94/911/137/13NoneOption D

Solution:

There are 26 black cards and 4 queen(2queen included in black cards)

P=(26C1+2C1)/52C1

28/52=7/13.

- A bag contains 12 Green and 8 White balls. Four balls are drawn out one by one and not replaced. What is the probability that they are in alternate colours?
310/2425308/4845284/2425273/4845NoneOption B

Solution:

P=12C1/20C1* 8C1/19C1*11C1/18C1*7C1/17C1

=12/20*8/19*11/18*7/17

=308/4845.

- From a group of 4 men, 5 women and 3 children, 4 people are to be chosen to form a committee. What is the probability that the committee contains at least 1 each of men, women and children?
16/216/1110/117/11NoneOption B

Solution:

No of ways 2M+1W+1C or 1M+2W+1C or 1M+1W+2C

P=(4C2*5C1*3C1 + 4C1*5C2*3C1+ 4C1*5C1*3C2)/12C4

=(90+120+60)/495

=270/495=6/11.

- 8 persons are seated at a round table. What is the probability that 3 particular persons sit together?
2/94/91/72/7NoneOption C

Solution:

3 particular person always sit together, then total person =5+1=6

6 persons will sit in (6-1)!=5! At round table.

No of ways in which 3 persons always sit together=5!*3!

No of ways of sitting 8 persons at round table=(8-1)!=7!.

Then P= (5!*3!)/7! =1/7.

- In a lottery, there are 12prizes and 25 blanks. A lottery is drawn at random. What is the probability of getting a prize?
12/371/915/372/7NoneOption A

Solution:

P=12C1/37C1

=12/37.

**Question 7-8:** In a bag , there are 5 Blue, 7 white and some Red balls. A ball is randomly selected and the probability that the ball is red is 2/5.

- ind the total number of balls?
22241820NoneOption D

Solution:

Total probability=1

P(Red)=2/5

Then P(Blue and White)=1-2/5=3/5

3/5………. 12(5+7)

1 ……… ?==> 20balls.

- If two balls are selected randomly, then what is the probability the selected balls are of same colour?
47/19059/19013/8017/80NoneOption B

Solution:

P(balls are of same colour)=(5C2+7C2+8C2)/20C2

=(10+21+28)/190

=59/190.

- A and B wrote an exam. The probability of A’s pass is 2/7 and the probability of B’s pass is 2/5. What is the probability that only one of them is passed out?
17/354/718/353/7NoneOption C

Solution:

A’= A’s fail and B’= B’s fail.

Therefore, p(A) = 2/7 and p(B) = 2/5,

P(A’) = 1 – P(A) = 1- 2/7 = 5/7 and P(B’) = 1- P(B) = 1- 1/5 = 4/5

Required probability= (2/7 * 4/5) + (2/5 * 5/7)

= (8/35 + 10/35) = 18/35.

- In a school, 35% of the students play chess,45% play carom and 10% play both. If a student is selected at random, then the probability that he plays chess or carom is
1/102/57/103/10NoneOption C

Solution:

P(A or B)=P(A) + P(B)-P(A and B)

=35/100+45/100-10/100

=70/100=7/10.

THANK U MAM

Hiii from odisha??

yes..

No9-p(b)=2/5(not 1/5)

No3-again starting from white

🙂