A bag contains 40 balls out of which some are red, some are blue and remaining are black. If the probability of drawing a red ball is 11/20 and that of blue ball is 1/5 ,then the number of black balls is
(A) 5 (B) 25 (C) 10 (D) 30

NCERT Class X
Mathematics - Exemplar Problems

Chapter _QUESTION PAPER SET II

2

Answers

2015-06-09T21:00:27+05:30
No. of red balls = 11/20*40 = 22
No. of blue balls = 1/5*40 = 8
So, no. of black balls = (40-22-8) = 10
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2015-06-09T21:01:00+05:30
The correct answer is option c i.e 10 balls
since there are 22 red and 8 blue balls
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