Question

Taylor leaves her house and bikes north at a constant speed of $10$ miles per hour. If her dad leaves the same house two hours later, driving north at a constant speed of $15$ miles per hour, how long will it take him, in hours, to reach Madison?

• A. $2$
• B. $3$
• C. $4$
• D. $5$

Answer 1

The correct option is C $4$

The distance covered by both will be the same.

Let '$t$' denote the time taken by Taylor to reach north then the time taken by her dad will be $t-2$.

We know that distance is speed multiplied by time.
Therefore $10\left(t\right)=15(t-2)$

$\Rightarrow 10t=15t-30$

$\Rightarrow 5t=30$

$\Rightarrow t=6$

Thus the time taken by her dad will be $t-2=6-2=4$.