The time to drive from Gotham City to Farmville varies inversely with the average speed. If the drive takes 6.2 hours at 42 mph, then how long will it take at 63 mph? Round to the nearest tenth of an hour.
A) 4.1 hours
B) 3.5 hours
C) 3.2 hours
D) 3.7 hours

Question

Quizplus · Accepted Answer

The time to drive varies inversely with speed, so $T = \frac{k}{v}$, where $T$ is time, $v$ is speed, and $k$ is a constant. Given $T = 6.2$ hours at $v = 42$ mph, we find $k = 6.2 \times 42$. To find the time at $63$ mph, solve $T = \frac{k}{63}$, substituting $k$ from the first part. This gives $T = \frac{6.2 \times 42}{63} = 4.13$, which rounds to $4.1$ hours.

The Time to Drive from Gotham City to Farmville Varies