1) Three unbiased coins are tossed. What is the probability of getting at least 2 tails?  Published on 06 Jul 15
a. 0.75
b. 0.5
c. 0.25
d. 0.2
Answer
Explanation

ANSWER: 0.5
Explanation: S = {HHH, HHT, HTH, HTT, THH, THT, TTH, TTT} E = {HTT, THT, TTH, TTT} n(S) = 8 n(E) = 4 P(E) =n(E) / n(S) = 4/8 = 0.5


2) Two friends A and B apply for a job in the same company. The chances of A getting selected is 2/5 and that of B is 4/7. What is the probability that both of them get selected?  Published on 06 Jul 15
a. 8/35
b. 34/35
c. 27/35
d. None of these
Answer
Explanation

ANSWER: 8/35
Explanation: P(A) = 2/5 P(B) = 4/7 E = {A and B both get selected} P(E) = P(A)*P(B) = 2/5 * 4/7 = 8/35


3) Tickets numbered 1 to 50 are mixed and one ticket is drawn at random. Find the probability that the ticket drawn has a number which is a multiple of 4 or 7?  Published on 06 Jul 15
a. 9/25
b. 9/50
c. 18/25
d. None of these
Answer
Explanation

ANSWER: 9/25
Explanation: S = {1, 2, 3, … , 49, 50} E = {4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 7, 14, 21, 35, 42, 49} n(S) = 50 n(E) = 18 P(E) = n(E)/n(S) = 18/50 = 9/25


4) Two dice are tossed simultaneously. Find the probability that the total is a prime number.  Published on 15 Jun 15
a. 7/9
b. 5/12
c. 1/6
d. 5/9
Answer
Explanation

ANSWER: 5/9
Explanation: No explanation is available for this question!


5) A class consists of 15 girls and 10 boys. Three students are to be randomly selected. Find the probability that one boy and two girls are picked.  Published on 15 Jun 15
a. 1/50
b. 3/25
c. 21/46
d. 25/122
Answer
Explanation

ANSWER: 21/46
Explanation: No explanation is available for this question!


6) A dice is rolled twice. What is the probability of getting sum 9?  Published on 12 Jun 15
a. 2/3
b. 1/3
c. 1/9
d. 3/9
Answer
Explanation

ANSWER: 1/9
Explanation: Possible event = 6*6 = 36
Favourable outcomes= {(3, 6), {4, 5}, {5, 4}, (6, 3)}
Thus probability; favourable/total = 4/36
=> 1/9


7) A box has 10 black and 10 white balls. What is the probability of getting two balls of the same color?  Published on 12 Jun 15
a. 10/19
b. 9/38
c. 9/19
d. 5/38
Answer
Explanation

ANSWER: 9/19
Explanation: No explanation is available for this question!


8) Three coins are tossed. What is the probability of getting at most two tails?  Published on 19 Oct 15
a. 7/8
b. 1/8
c. 2/8
d. 4/8
Answer
Explanation

ANSWER: 7/8
Explanation: It is given that 3 coins are tossed simultaneously.
=>Total outcomes when one coin is tossed=2
=>Total outcomes when 3 coins are tossed= 2n = 2 X 2 X 2
=8 outcomes
Favourable outcomes: TTH, THT, HTT, THH, THT,HHT,HHH=7
Therefore, Probability= 7/8

