Probability Ques 33
Question-
There are 5 red, 6 black and 5 blue balls in a bag. Out of these balls, four balls are picked at random from the bag. Then, what is the probability that one is red, two are black and one is blue ball?
(1) $\frac{75}{362}$
(2) $\frac{75}{364}$
(3) $\frac{71}{362}$
(4) $\frac{70}{363}$
(5) $\frac{5}{26}$
IBPS RRBs Officer CWE (Prelim Exam) 04.08.2019
Show Answer
Correct Answer: (2)
Solution: (2)
Total possible outcomes $=$ selection of 4 balls out of 16 balls $=16_{C_{4}}=\frac{16 \times 15 \times 14 \times 13}{1 \times 2 \times 3 \times 4}$ $=1820$
Total favourable outcomes $=5_{C_{1}} \times 6_{C_{2}} \times 5_{C_{1}}$ $=5 \times \frac{6 \times 5}{1 \times 2} \times 5$ $=5 \times 15 \times 5=375$
Required probability $=\frac{375}{1820}=\frac{75}{364}$
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