Question

Places A and B are 100 km apart on a highway. One car starts from A and another from B at the same time. If the cars travel in the same direction at different speeds, they meet in 5 hours. If they travel towards each other, they meet in 1 hour. What are the speeds of the two cars? 

(A) 60 km/hr, 40 km/hr 

(B) 30 km/hr, 70 km/hr 

(C) 20 km/hr, 80 km/hr 

(D) More than one of the above 

(E) None of the above

Answer 1

Correct option is (A) 60 km/hr, 40 km/hr   

Let the speed of car at A be x kmph

and the speed of car at B be y kmph

when the car travel in same direction Relative Speed is x - y

Dist = 100km

t = 5hours

∴ Dist = S×T

100 = (x-y)5

x-y = 20   ⟶(I)

when the car travel in opp direction Relative Speed is x + y

Dist = 100km

t = 1hours

Dist = ST

100 = (x+y)1

x+y = 100⟶(II)

Solving (I) & (II)

x − y = 20 .....(I)

x + y = 100 ....(II)

2 x = 120 

x = 60 km/h 

y = 40 km/h

Speed of the car at A = 60km/h

Speed of the car at B = 40km/h