Q. If a coin is flipped three times, what is the probability of getting exactly two heads?
A.3/8
B.1/2
C.1/4
D.1/8
Solution
The total outcomes are 2^3 = 8. The combinations for exactly 2 heads are HHT, HTH, THH, which gives us 3 favorable outcomes. So, the probability is 3/8.
Correct Answer: A — 3/8
Q. If a coin is tossed three times, what is the probability of getting at least one head?
A.1/8
B.1/2
C.7/8
D.3/8
Solution
The probability of getting no heads (all tails) is (1/2)^3 = 1/8. Therefore, the probability of getting at least one head is 1 - 1/8 = 7/8.
Correct Answer: C — 7/8
Q. If a coin is tossed three times, what is the probability of getting exactly two heads?
A.3/8
B.1/2
C.1/4
D.5/8
Solution
The number of ways to get exactly 2 heads in 3 tosses is 3 (HHT, HTH, THH). The total outcomes are 2^3 = 8. So, the probability is 3/8.
Correct Answer: A — 3/8
Q. In a class of 30 students, 18 are girls. If a student is chosen at random, what is the probability that the student is a boy?
A.1/3
B.2/5
C.1/2
D.3/5
Solution
The number of boys is 30 - 18 = 12. The probability is 12/30 = 2/5.
Correct Answer: A — 1/3
Q. In a class of 30 students, 18 are girls. If a student is selected at random, what is the probability that the student is a boy?
A.0.4
B.0.6
C.0.5
D.0.3
Solution
The number of boys is 30 - 18 = 12. The probability is 12/30 = 0.4.
Correct Answer: B — 0.6
Q. In a lottery, there are 10 tickets, and 3 of them are winning tickets. What is the probability of picking a winning ticket?
A.1/10
B.1/3
C.3/10
D.1/5
Solution
The probability of picking a winning ticket is 3/10.
Correct Answer: C — 3/10
Q. In a lottery, there are 100 tickets, and 10 of them are winning tickets. What is the probability of picking a winning ticket?
A.1/10
B.1/5
C.1/20
D.1/50
Solution
The probability of picking a winning ticket is 10/100 = 1/10.
Correct Answer: B — 1/5
Q. Two coins are tossed. What is the probability of getting at least one head?
A.1/4
B.1/2
C.3/4
D.1/3
Solution
The possible outcomes are HH, HT, TH, TT. The outcomes with at least one head are HH, HT, TH. So, the probability is 3/4.
Correct Answer: C — 3/4
Q. Two dice are rolled. What is the probability that the sum of the numbers on the dice is 7?
A.1/6
B.1/12
C.1/36
D.5/36
Solution
The combinations that give a sum of 7 are (1,6), (2,5), (3,4), (4,3), (5,2), (6,1). There are 6 combinations out of 36 total outcomes, so the probability is 6/36 = 1/6.
