Question

Two cars started at the same time, from the same point, driving along the same road. The rate of the first car is $50$mph and the rate of the second car is $60$mph. How long will it take for the distance between the two cars to be $30$ miles

• A. $2$ hours
• B. $3$ hours
• C. $4$ hours
• D. $5$ hours

Answer 1

The correct option is B $3$ hours

Let $D_1$ and $D_2$ be the distances travelled by the two cars in t hours

$D_1=50t$ and $D_2=60t$

The second has a higher speed and therefore the distance d between the two cars is given by,

$d=60t-50t=10t$

For $d$ to be $30$ miles, we need to have

$30miles=10t$

Solve the above equation for $t$ to obtain

$t=3$ hours