Question

Arun, Barun and Kiranmala start from the same place and travel in the same
direction at speeds of 30, 40 and 60 km per hour respectively. Barun starts two
hours after Arun. If Barun and Kiranmala overtake Arun at the same instant, how
many hours after Arun did Kiranmala start?
(1) 3
(2) 3.5
(3) 4
(4) 4.5
(5) 5

Answer 1

according to me (2) 3.5 please check if correct

Answer 2

Answer:

Kiranmala will start after option (3) 4 hours

Step-by-step explanation:

Let they overtake Arun after x hours when Arun starts.

=> distance travel by Arun = 30x

Barun starts after 2 hours

=> time taken by Barun to overtake Arun = x - 2

=> Distance traveled by Barun = 40(x - 2)

Since distance traveled is same

=> 40(x - 2) = 30x

=> 40x - 80 = 30x

=> 10x = 80

=> x = 8 hrs

Let Kiranmala starts after h hours of Arun

=> time taken by Kiranmala to overtake Arun = 8 - h

=> Distance traveled by kiranmala = 60(8-h) = 240

=> 480 - 60h = 240

=> 60h = 240

=> h = 4 hours

Hence Kiranmala starts after option (3) 4 hours