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.
My thought process if it helps anyone:
B and K overtake A at the same instant, this little phrase tells us everything we need to solve the question. This means that the distance traveled by A, B, and K are equal.
Let's say A travels for
T hours. B started 2 hours after A, so that means B travels for
T-2 hours.
Hence:
distance traveled by A = distance traveled by B
30t = 40(t-2)
t = 8
Total distance traveled by A, B and K = 240 kilometers. It takes K 4 hours to travel 240 km, hence K started 4 hours after A.