In a recent chess tournament, three players, Alex, Jamie, and Chris, competed for the title of champion. The probabilities of Alex, Jamie, and Chris winning were 1/5, 1/4, and 1/8 respectively. What is the probability that either Alex or Jamie emerged as the champion?

Answer Choices

Correct answer marked below

1/8

7/20

9/20

Correct

11/20

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Explanation

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Official Explanation

Official

To find the probability that either Alex or Jamie wins, we can use the formula P(Alex or Jamie) = P(Alex) + P(Jamie) - P(both). Since only one player can win, P(both) = 0. Therefore, P(Alex or Jamie) is simply the sum of their individual probabilities. We calculate this as follows: P(Alex) = 1/5 and…

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Comments

SamidhaFeb 1, 2024

Tricky wording but good practice

YHAug 29, 2024

pls explain more?

What this question tests

What it tests

Your ability to compute probabilities of single and compound events, including 'at least one' questions.

Common trap

Forgetting to use the complement for 'at least one', or treating dependent events as independent.