The slow cars

Algebra Level 1

Ben left his apartment at 1:00, and Frank left at 2:00. Ben drove at 10 miles per hour, and Frank drove at 20 miles per hour. What time did Frank catch up? (Assuming that they drove the same route!)

3:00 3:30 2:30 4:00

1 solution

A Former Brilliant Member
Jun 24, 2018

The distance covered by Ben must be equal to the distance covered by Frank. Let $t$ be the total time covered by Frank. Use the formula $d=Vt$ where $d$ is the distance, $V$ is the speed and $t$ is the time. The total time covered by Frank is $d=20t$ and the total time covered by Ben is $d=10(1+t)$ . Then

$d=d$

$20t=10(1+t)$

$20t=10+10t$

$10t=10$

$t=1~hour$

So the required answer is $2:00+1=\boxed{3:00}$

The slow cars

1 solution

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