A box contains 21 balls numbered 1 to 21 A ball is drawn and then another ball is drawn without repl...........

Quantitative Aptitude ( CCS) Probability

A box contains 21 balls numbered 1 to 21. A ball is drawn and then another ball is drawn without replacement. What is the probability that both balls are even numbered?

2/7

8/21

3/14

5/21

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Explanation:

There are 10 even numbers in the group 1-21.

∴ The probability that the first ball is even numbered =	10/
	21

Since the ball is not replaced there are now 20 balls left, of which 9 are even numbered.

∴ The probability that the second ball is even numbered =	9/
	20

∴ Required probability =	10/	×	9/	=	9/	=	3/
	21		20		42		14

Hence, option 3 is thr correct answer.

By: Amit Kumar

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A box contains 21 balls numbered 1 to 21 A ball is drawn and then another ball is drawn without repl...........

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