Question

John went to his friend’s house. For the first $2$ hours, he drove at $55$ mph. For the next hour, he drove at a speed of $70$ mph. For the final 2 hours, he drove at $50$ mph. If he drove the entire trip at 70 mph, how much time could he save?

• A. $1/2$ hour
• B. $3$ hours
• C. $1$ hour
• D. $2$ hours

Answer 1

The correct option is C $1$ hour

Speed in the first $2$ hours $=55$ mph
Distance traveled in the first $2$ hours $=2\times 55=110$ miles
Speed in the third hour $=70$ mph
Distance traveled in the third hour $=70$ miles
Speed during the last $2$ hours $=50$ mph
Distance traveled in the last 2 hours $=2\times 50=100$ miles
Total distance traveled $=110$ miles $+70$ miles $+100$ miles $=280$ miles
Time taken to travel $280$ miles $=5$ hours
Time taken for traveling $280$ miles at the speed of $70$ mph $=\frac{280}{70}=4$ hours
John could have saved one hour.