Suppose you spin the spinner 5 times. means “the probability of getting a vowel on exactly 3 of the spins.”

A success is getting a vowel on one spin. Getting a vowel on exactly 3 of the 5 spins is therefore P(3 successes), which is choice A. P(4 successes) and P(5 successes) describe getting vowels on four or all five spins.

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