Question

A car driver, driving in a fog, passes a pedestrian who was walking at the rate of 2 km/h in the same direction. The pedestrian could see the car for 6 min and it was visible to him up to a distance of 0.6 km. What was the speed of the car?

• A. 15 km/h
• B. 30 km/h
• C. 20 km/h
• D. 8 km/h

Answer 1

The Correct Option is D

Relative speed formula in same direction
S1 and S2 be the speeds of car and passenger respectively and L be the distance travelled.

S1-S2 \(=\frac{(L1+L2)}{T}\)

So in the question S1 \(=\frac{2km}{hr}\)

L1+L2=0.6km
T=6min so to covert in hour

6min \(=\frac{1}{10hr}\)

So put all the values in the formula
S1-2 = (0.6)\(\times\)10

S1 \(=\frac{8km}{hr}\)
So the correct option is (D)