Quants problem

lekshya

Deepak starts from A at 10.00 am at a speed of 45 km/hr and Sudhir starts from B at the same time at speed of 50 km/hr towards each other. They meet at 10.11 am but keep moving till they reach at ends (Deepak at B & Sudhir at A), then they turn back and keep moving. At what time do they meet again?

can any one solve this question in both detailed and shortcut method?

puneet_ece

ya..i have solved it...

SaswatPadhi

Quite simple question ..

The detailed solution :
(S = Sudhir and D = Deepak)

Relative speed between S and D = 50 + 45 = 95 km/hr
Time taken to meet = 11 min
So, distance between them = 11 * 95 / 60 km = 17.4167 km (approx.)
After 11 more mins, S will be at A and D will be at B, because they will cover the same relative distance i.e. 17.4167 km from the point of meet.
After 11 more mins, they meet again, because they will cover the same relative distance i.e. 17.4167 km from the ends - similar to initial travel.

So, in total, they travel for 11+11 mins more = 22 mins more. So, they meet again at 10:33.


The Short-Cut solution :

For any question of this kind, just use the following formula :

Time of next meet = Starting Time + 3 * (Time of first meet - Starting Time)

So, Time of next meet = 10:00 + 3 * (10:11 - 10:00) = 10:33

saurabh616

thanks
from where do you get this formula

what does '3' signifies here

jackyork

Nice and smart. Thanks a lot!!