AnswersGrade 7 MathematicsEquations — TestQuestion 20
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Equations — Test

Question 20 • Grade 7 Mathematics

Mia spent 30 minutes answering the math questions on the exam. This was 3 fifths of the total amount of time allotted for this section of the exam. To determine the total amount of time allotted for this section of the exam, Mia set up and solved the equation as shown. Mia's Work 3 fifths x is equal to 30 5 thirds 3 fifths x is equal to 30 times 3 fifths x is equal to 18 Which best describes the error that Mia made?

Answer
A
Mia did not use the correct equation to model the given information.
B
Mia should have multiplied both sides of the equation by 5 thirds .
C
The product of 5 thirds and 1 over 30 should have been the value of x .
D
The product of 30 times 3 fifths is not equal to 18 .

Explanation

The equation 3/5 x = 30 correctly represents that 30 minutes is 3/5 of the total time x. To solve for x, Mia should multiply both sides by the reciprocal, 5/3, giving x = 30 × 5/3 = 50 minutes. Instead, she multiplied by 3/5, so she used the wrong operation to isolate x. The correct choice is B: Mia should have multiplied both sides by 5/3.

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