Blackbox wrote:
A, B, K start from the same place and travel in the same direction at speeds of 30km/hr, 40km/hr, 60km/hr respectively. B starts two hours after A. If B and K overtake A at the same instant, how many hours after A did K start?
A) 3
B) 4.5
C) 4
d) 5.5
e) 5
Please include your explanation.
Let a be travelling for x hours.
Then b was travelling for x-2 hours.
K was travelling for x-y hrs.
It is given that B,K overtake A at the same instant on the same track and from same starting point,so all 3 should have travelled same distance.
Distance(A) = Distance(B) = Distance(K)
30*x = 40*(x-2) -> using distance(A) and distance(B)
x = 8
and
40*(x-2) = 60*(x-y) -> using distance(B) and distance(K)
40*(6) = 60*(8-y)
12 =24-3y
y = 4