A jeep is chasing a car which is 5 km ahead. Their respective speeds are 90 km/hr and 75 km/hr. After how many minutes will the jeep catch the car ?

Answer: Option B

Their relative speed in same direction
= (90 - 75) kmph
= 15 kmph
Time taken by jeep to catch car :
$$\begin{array}{rl}& =\frac{5}{15}\text{ hour}\\ & =\frac{1}{3}\text{ hour}\\ & =\frac{1}{3}\times 60\text{ min}\\ & =20\text{ min}\end{array}$$