Solve the problem.
-A private airplane leaves an airport and flies due east at $175 \mathrm{mph}$. Two hours later, a jet leaves the same airport and flies due east at $315 \mathrm{mph}$. When will the jet overtake the plane?
A) $4 \frac{1}{2} \mathrm{hr}$
B) $\frac{5}{9} \mathrm{hr}$
C) $1 \frac{4}{5} \mathrm{hr}$
D) $2 \frac{1}{2} \mathrm{hr}$

Question

Quizplus · Accepted Answer

The airplane has a 2-hour head start, so it travels $2 \times 175 = 350$ miles before the jet starts. The relative speed of the jet compared to the airplane is $315 - 175 = 140$ mph. To overtake the airplane, the jet needs to cover the 350-mile head start, which takes $350 \div 140 = 2.5$ hours.

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