DAT Quantitative Reasoning: Probability 3 — Questions and Answers
Question 1: A box has 3 white, 2 black, and 5 gray balls. What is the probability of drawing a black ball?
- 1/5 (Correct answer)
- 2/5
- 1/3
- 1/10
Correct answer: 1/5
There are 2 black out of 10 total, so 2/10 = 1/5.
Question 2: What is the probability of drawing a heart OR a spade from a standard deck?
- 1/2 (Correct answer)
- 1/4
- 1/13
- 3/4
Correct answer: 1/2
Hearts and spades make 26 of 52 cards, so 1/2.
Question 3: If you draw two cards without replacement, what is the probability both are aces?
- 1/221 (Correct answer)
- 1/169
- 1/13
- 1/52
Correct answer: 1/221
(4/52) × (3/51) = 12/2652 = 1/221.
Question 4: A jar has 5 green and 5 yellow candies. What is the probability of drawing green twice with replacement?
- 1/4 (Correct answer)
- 1/2
- 1/5
- 2/5
Correct answer: 1/4
Each draw is 1/2, so 1/2 × 1/2 = 1/4.
Question 5: The probability of rain is 0.4 and snow is 0.1, mutually exclusive. What is the probability of either?
- 0.5 (Correct answer)
- 0.04
- 0.3
- 0.45
Correct answer: 0.5
For mutually exclusive events, add: 0.4 + 0.1 = 0.5.
Question 6: A die is rolled. What is the probability of an odd number or a 6?
- 2/3 (Correct answer)
- 1/2
- 1/3
- 5/6
Correct answer: 2/3
Odds are 1,3,5 plus 6 gives 4 outcomes, so 4/6 = 2/3.
Question 7: If P(A) = 0.6, P(B) = 0.5, and they are independent, what is P(A and B)?
- 0.30 (Correct answer)
- 1.10
- 0.11
- 0.55
Correct answer: 0.30
For independent events, multiply: 0.6 × 0.5 = 0.30.
DAT Quantitative Reasoning: Probability 3
A box has 3 white, 2 black, and 5 gray balls.
What is the probability of drawing a black ball?