fitzpratik wrote:

A box contains only red chips, green chips and blue chips. If a chip is randomly selected from the box, what is the probability that the chip is either red or green?

A. The probability of selecting green chip is 1/3

B. The Probability of selecting a blue chip is 1/7

Target question: What is the probability that the chip is either red or green? Given: The box contains only red chips, green chips and blue chips Statement 1: The probability of selecting green chip is 1/3This tells us that 1/3 of the chips are GREEN, but there's no information about the RED chips.

Consider these two possible cases:

Case a: There are 6 chips in total. 2 chips are green, and 2 chips are red. In this case, the answer to the target question is

P(chip is red or green) = 4/6Case b: There are 6 chips in total. 2 chips are green, and 3 chips are red. In this case, the answer to the target question is

P(chip is red or green) = 5/6Since we cannot answer the

target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: The probability of selecting a blue chip is 1/7 This also tells us that

the probability of selecting a NON-BLUE chip is 6/7Since the box contains only red chips, green chips and blue chips, then selecting a NON-BLUE chip is the same as selecting either a RED chip OR a green chip

In other other words, P(select NON-BLUE chip) = P(selecting either a RED chip OR a green chip)

So, the answer to the target question is

P(chip is red or green) = 6/7Answer: B

Cheers,

Brent

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