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

Answer: (D)

8 km/h

Answer 2

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)