Back to Solve multi-step real-life and mathematical problems with positive and negative rational numbers — Problem 5 · Task Set 9

Solving Multi-Step Problems with Rational Numbers

23 problems·~30 min·Common Core Math - Grade 7·standard·7-ee-b-3

Work through problems with immediate feedback

Fluency

A student calculated that a plumber earned $146.25 by working 4.5 hours at $31.50 per hour and then paying a $15.75 supply fee. Which estimation best checks whether $146.25 is reasonable?

Round to $30 \times 5 - 16 = 150 - 16 = 134$ , which is close to $146.25.

Round to $30 \times 4 - 15 = 120 - 15 = 105$ , which is far from $146.25, so the answer is wrong.

Round to $35 \times 5 - 15 = 175 - 15 = 160$ , which shows $146.25 is too low.

"About $140" is close enough; no calculation is needed.