Take timed practice tests on Probability for JEE Main and JEE Advanced with session-wise drills, score review, and explanation-led revision.
Six 20-question timed sessions plus one 60-question module test. Each question is original and calibrated from the uploaded material pattern without copying PDF wording.
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1. A fair die is rolled. The probability of getting a prime number is:
Explanation: Primes on a die: {2, 3, 5} = 3 outcomes. Total outcomes = 6. P = 3/6 = 1/2.
2. Two coins are tossed. The number of elements in the sample space is:
Explanation: Each coin has 2 outcomes (H or T). Two coins: 2 × 2 = 4 outcomes: {HH, HT, TH, TT}.
3. If P(A) = 0.3, then P(A') is:
Explanation: P(A') = 1 − P(A) = 1 − 0.3 = 0.7. The complement rule.
4. If P(A) = 0.4, P(B) = 0.3, and A and B are mutually exclusive, then P(A ∪ B) is:
Explanation: For mutually exclusive events: P(A ∪ B) = P(A) + P(B) = 0.4 + 0.3 = 0.7.
5. P(A|B) is defined as:
Explanation: Conditional probability of A given B: P(A|B) = P(A ∩ B)/P(B), provided P(B) > 0.
6. If A and B are independent events with P(A) = 0.3 and P(B) = 0.4, then P(A ∩ B) is:
Explanation: For independent events: P(A ∩ B) = P(A) × P(B) = 0.3 × 0.4 = 0.12.
7. A bag has 3 red and 2 blue balls. Two balls drawn without replacement. P(2nd is red | 1st is red) is:
Explanation: After drawing 1 red ball, remaining: 2 red + 2 blue = 4 balls. P(2nd red | 1st red) = 2/4 = 1/2.
8. A fair coin is tossed. If heads, one fair die is rolled; if tails, two fair dice are rolled. What is the probability that at least one rolled die shows 6?
Explanation: Given heads, the probability is $1/6$. Given tails, it is $1-(5/6)^2=11/36$. By total probability, $P=\frac12(1/6)+\frac12(11/36)= 17/72 $.
9. In 5 tosses of a fair coin, the probability of getting exactly 3 heads is:
Explanation: Using Binomial: P(X=3) = C(5,3)(1/2)³(1/2)² = 10 × (1/32) = 10/32.
10. A card is drawn from a deck of 52. P(it is a face card or a heart) is:
Explanation: Face cards: 12. Hearts: 13. Face cards that are hearts: 3. By inclusion-exclusion: 12 + 13 − 3 = 22. P = 22/52.
11. A number is chosen at random from 1 to 20. The probability that it is divisible by 3 or 5 is:
Explanation: Divisible by 3: {3,6,9,12,15,18} = 6 numbers. Divisible by 5: {5,10,15,20} = 4 numbers. Divisible by 15: {15} = 1. By inclusion-exclusion: 6 + 4 − 1 = 9. P = 9/20.
12. If P(A) = 2/5, P(B) = 3/10, P(A ∩ B) = 1/5, then P(A' ∩ B') is:
Explanation: P(A ∪ B) = P(A) + P(B) − P(A ∩ B) = 2/5 + 3/10 − 1/5 = 4/10 + 3/10 − 2/10 = 5/10 = 1/2. P(A' ∩ B') = P((A ∪ B)') = 1 − 1/2 = 1/2.
13. Bag I has 3 red, 4 black. Bag II has 5 red, 6 black. A bag is selected at random and a red ball is drawn. P(it came from Bag I) is:
Explanation: By Bayes' theorem, $P(I|R)=[(1/2)(3/7)]/[(1/2)(3/7)+(1/2)(5/11)]=(3/7)/(3/7+5/11)= 33/68 $.
14. If X is a binomial random variable B(n, p) with mean 6 and variance 2, then n equals:
Explanation: Mean = np = 6, Variance = np(1−p) = 2. So np(1−p)/(np) = 2/6 → 1−p = 1/3 → p = 2/3. Then n = 6/p = 6/(2/3) = 9.
15. Two distinct numbers are randomly selected from {1, 2, 3, 4, 5}. The probability that their product is even is:
Explanation: There are $\binom52=10$ pairs. A product is odd only if both numbers are chosen from {1,3,5}, which gives $\binom32=3$ pairs. Hence the required probability is $1-3/10= 7/10 $.
16. The probability of an impossible event is:
Explanation: An impossible event cannot occur, so its probability is 0. A certain event has probability 1.
17. Three unbiased coins are tossed. P(at least one head) is:
Explanation: P(at least 1 head) = 1 − P(no heads) = 1 − (1/2)³ = 1 − 1/8 = 7/8.
18. If A and B are independent, P(A) = 0.4, P(B) = 0.5, then P(A ∪ B) is:
Explanation: P(A ∪ B) = P(A) + P(B) − P(A ∩ B) = 0.4 + 0.5 − (0.4 × 0.5) = 0.9 − 0.2 = 0.7.