Question tom-sc

5.1 Linear Inequalities in One or Two Variables - Solving single-variable inequalities
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Tom scored 85, 78, and 98 on his first three exams in history class. Solving which inequality gives the score, G, on Tom’s fourth exam that will result in a mean score on all four exams of at least 90 ?

A.

90 minus, open parenthesis, 85 plus 78 plus 98, close parenthesis, is less than or equal to 4 G

B.

4 G, plus 85, plus 78, plus 98, is greater than or equal to 360

C.

the fraction with numerator, open parenthesis, G plus 85 plus 78 plus 98, close parenthesis, and denominator 4, end fraction, is greater than or equal to 90

D.

the fraction with numerator, open parenthesis, 85 plus 78 plus 98, close parenthesis, and denominator 4, end fraction, is greater than or equal to 90 minus 4 G

Tom scored 85, 78, and 98 on his first three exams in history class. Solving which

Medium-difficulty · SAT Math · Linear Inequalities in One or Two Variables — Solving single-variable inequalities. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice C is correct. The mean of the four scores (G, 85, 78, and 98) can be expressed as  the fraction with numerator G, plus 85, plus 78, plus 98, and denominator 4. The inequality that expresses the condition that the mean score is at least 90 can therefore be written as the fraction with numerator G, plus 85, plus 78, plus 98, and denominator 4, is greater than or equal to 90.

Choice A is incorrect. The sum of the scores (G, 85, 78, and 98) isn’t divided by 4 to express the mean. Choice B is incorrect and may be the result of an algebraic error when multiplying both sides of the inequality by 4. Choice D is incorrect because it doesn’t include G in the mean with the other three scores.