Distance Mr Tan travelled in the first 30 min

= 30 min x 90 m/min
= 2700 m


0800 + 0030 = 0830

Mr Ang started at 8.30 am.
And when he started, Mr Tan is 2700m ahead of him.

360 m/min - 90 m/min = 270 m/min


Every minute, Mr Ang travels 270m more than Mr Tan.

So this means the gap/distance between them will be shortened by 270 m every minute. In other words, he will get 270 m closer to Mr Tan every minute.


2700m ÷ 270 m/min = 10 min


He will need 10 minutes to close up that 2700m distance/gap between them , catch up with him and overtake him.



0830 + 0010 = 0840

He will overtake Mr Tan at 8.40am

Alternate working :


Since Mr Ang started 30 minute after Mr Tan,

Let number of minutes Mr Ang travelled be 1 unit

Then number of minutes Mr Tan travelled
= 1 unit + 30


When Mr Ang overtakes Mr Tan, the total distance each of them travelled is the same.


Distance = speed x time

Mr Ang's distance
= 1 unit min x 360 m/min
= 360 unit m

Mr Tan's distance
= (1 unit + 30)min x 90 m/min
= 90 unit m + 2700 m

Since the distance is equal,

360 unit m = 90 unit m + 2700 m

360 unit m - 90 unit m = 2700 m

270 unit m = 2700 m

1 unit = 2700m ÷ 270 m = 10

So 1 unit is 10 and therefore Mr Ang took only 10 minutes to overtake Mr Tan.

0800 + 0030 + 0010 = 0840