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04 Oct 2025, 20:55
Kudos
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E
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Difficulty:
35%
(medium)
Question Stats:
73% (01:35) correct
27%
(01:27)
wrong
based on 77
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A bowl contains balls that are either yellow, black, or white. If one ball is selected at random, what is the probability that the ball will be black?
(1) There are 7 more yellow balls than black balls in the bowl.
(2) The probability of selecting a white ball is the same as the probability of selecting a yellow ball.
(1) There are 7 more yellow balls than black balls in the bowl.
(2) The probability of selecting a white ball is the same as the probability of selecting a yellow ball.
05 Oct 2025, 02:18
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solutaearum
When we combine the statements we get:
White and yellow are equal, and each is 7 more than black, let black = b.
Then yellow = white = b + 7.
Total balls = b + (b + 7) + (b + 7) = 3b + 14.
Probability(black) = b/(3b + 14).
Because b can be any positive integer, this probability can vary. Since it’s not fixed, the data are insufficient.
Answer: E.
05 Oct 2025, 05:40
Kudos
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@solutaearum
A bowl contains balls that are either yellow, black, or white.
If one ball is selected at random, what is the probability that the ball will be black?
(1) There are 7 more yellow balls than black balls in the bowl.
Number of yellow balls = 7 + Number of black balls
But number of white balls / total balls is unknown
NOT SUFFICIENT
(2) The probability of selecting a white ball is the same as the probability of selecting a yellow ball.
Number of white balls = Number of yellow balls
But the number of black balls is unknown
NOT SUFFICIENT
(1) + (2)
(1) There are 7 more yellow balls than black balls in the bowl.
Number of yellow balls = 7 + Number of black balls
(2) The probability of selecting a white ball is the same as the probability of selecting a yellow ball.
Number of white balls = Number of yellow balls
Number of yellow balls = 7 + Number of black balls = Number of white balls
Let the number of black balls be x
Number of yellow balls = Number of white balls = x + 7
Total balls = x + x+7 + x+7 = 3x + 14
If one ball is selected at random, the probability that the ball will be black = \(\frac{x}{3x+14}\)
Since x is unknown
NOT SUFFICIENT
IMO E
A bowl contains balls that are either yellow, black, or white.
If one ball is selected at random, what is the probability that the ball will be black?
(1) There are 7 more yellow balls than black balls in the bowl.
Number of yellow balls = 7 + Number of black balls
But number of white balls / total balls is unknown
NOT SUFFICIENT
(2) The probability of selecting a white ball is the same as the probability of selecting a yellow ball.
Number of white balls = Number of yellow balls
But the number of black balls is unknown
NOT SUFFICIENT
(1) + (2)
(1) There are 7 more yellow balls than black balls in the bowl.
Number of yellow balls = 7 + Number of black balls
(2) The probability of selecting a white ball is the same as the probability of selecting a yellow ball.
Number of white balls = Number of yellow balls
Number of yellow balls = 7 + Number of black balls = Number of white balls
Let the number of black balls be x
Number of yellow balls = Number of white balls = x + 7
Total balls = x + x+7 + x+7 = 3x + 14
If one ball is selected at random, the probability that the ball will be black = \(\frac{x}{3x+14}\)
Since x is unknown
NOT SUFFICIENT
IMO E
