SAT Linear inequalities in one or two variables Practice Question 7 (Medium)

Question bank / Linear inequalities in one or two variables

Math · AlgebraMedium

Priya's scores on her first three tests were $78$ , $88$ , and $90$ . What is the minimum score she must earn on her fourth test so that the average of her four test scores is at least $85$ ?

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Answer: 84

The average is at least 85 when $\frac{78 + 88 + 90 + x}{4} \ge 85$ . Multiply by 4: $256 + x \ge 340$ . Subtract 256: $x \ge 84$ .

Answering 85 assumes the fourth score must equal the target average, ignoring the scores she already has.

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