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A class contains six boys and 21 girls.
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What is the probability of selecting a girl if a student is selected at random?
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We begin by recalling that probability is the likelihood or chance of an event occurring.
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We know that the probability of an event occurring can be written as a fraction where the numerator is the number of favorable outcomes and the denominator is the total number of outcomes.
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In this question, we need to find the probability of selecting a girl if a student is selected at random.
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We are told that there are 21 girls, so our numerator will be 21.
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There are six boys, and six plus 21 is equal to 27.
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As there are 27 students altogether, the probability of selecting a girl is 21 out of 27.
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Both the numerator and denominator are divisible by three, so we can simplify our fraction.
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21 divided by three is equal to seven, and 27 divided by three is equal to nine.
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If a student from the class is selected at random, the probability of selecting a girl is seven out of nine or seven-ninths.