New One Goal, Three Exams: Strategies for Mastering RBI, SEBI, and IFSCA Exams
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Question

A bag contains 24 white and some black balls. If the probability of drawing a black ball from the bag is 1.5 times that of drawing a white ball, find the number of black balls in the bag.

A 20 Correct Answer Incorrect Answer
B 30 Correct Answer Incorrect Answer
C 26 Correct Answer Incorrect Answer
D 36 Correct Answer Incorrect Answer
E None of these Correct Answer Incorrect Answer

Solution

Number of white balls = 24
Let x be the number of black balls.
Total number of balls in the bag = 24 + x
Also, the probability of drawing a black ball from the bag is 1.5 times that of drawing a white ball.
⇒ x/(24 + x) = 1.5 [24/(24 + x)]
⇒ x = 1.45 × 24 = 36
Hence, the number of black balls in the bag = 36

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