Question

Two cars are moving in the same direction with a speed of $30\text{kmph}$. They are seperated from each other by $5\text{km}$. Third car moving in the opposite direction meets the two cars after an interval of 4 minutes. What is the speed of the third car?

• A. $30\text{kmph}$
• B. $35\text{kmph}$
• C. $40\text{kmph}$
• D. $45\text{kmph}$

Answer 1

The correct option is D $45\text{kmph}$

Using relative speed of third car, we have


$v+30=\frac{5\text{km}}{\left(\frac{4}{60}\right)\text{hour}}$
$\Rightarrow v+30=\frac{5\times 60}{4}=75$
$\Rightarrow v=75-30=45\text{km/h}$