Question

Bernardo drives to work at an average speed of $50$ miles per hour and returns along the same route at an average speed of $25$ miles per hour. If his total travel time is $3$ hours, what is the total number of miles in the round-trip?

• A. $225$
• B. $112.5$
• C. $100$
• D. $62.5$
• E. $50$

Answer 1

The correct option is C $100$

Bernardo travels the same distance at $25$mph as he does at $50$mph.

However, since $25$mph is only half of $50$mph, he must travel twice as long at $25$mph.

If we let the time he traveled $50$mph "$t$", then

$t+2t=3$
$\Rightarrow 3t=3$
$\Rightarrow t=1$
This means he traveled $1$ hour at $50$mph. In this time, he traveled $50$ miles. He traveled the same distance at $25$mph, so his total distance was
$50$ miles $+$ $50$ miles $=$ $100$ miles
Therefore, the total number of round trip was $100$ miles.

Hence, option C is correct.