Aptitude  Probability  Practice Q&A

1. In a class, there are 15 boys and 10 girls. Three students are selected at random. The probability that 1 girl and 2 boys are selected, is:

 $\dfrac{21}{46}$ $\dfrac{25}{117}$ $\dfrac{1}{50}$ $\dfrac{3}{25}$

2. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

 $\dfrac{1}{2}$ $\dfrac{2}{5}$ $\dfrac{8}{15}$ $\dfrac{9}{20}$

3. A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

 $\dfrac{10}{21}$ $\dfrac{11}{21}$ $\dfrac{2}{7}$ $\dfrac{5}{7}$

4. What is the probability of getting a sum 9 from two throws of a dice?

 $\dfrac{1}{6}$ $\dfrac{1}{8}$ $\dfrac{1}{9}$ $\dfrac{1}{12}$

5. Two cards are drawn together at random from a pack of 52 cards. What is the probability of both the cards being Queens?

 1/52 1/221 2/221 1/26

6. Three unbiased coins are tossed. What is the probability of getting at most two heads?

 $\dfrac{3}{4}$ $\dfrac{1}{4}$ $\dfrac{3}{8}$ $\dfrac{7}{8}$

7. A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:

 $\dfrac{1}{22}$ $\dfrac{3}{22}$ $\dfrac{2}{91}$ $\dfrac{2}{77}$

8. Two cards are drawn together from a pack of 52 cards. The probability that one is a club and one is a diamond?

 13/51 1/52 13/102 1/26

9. John and Dani go for an interview for two vacancies. The probability for the selection of John is 1/3 and whereas the probability for the selection of Dani is 1/5. What is the probability that only one of them is selected?

 3/5 None of these 2/5 1/5