Varsha lives alone and dislikes cooking, so sh...

Varsha lives alone and dislikes cooking, so she goes out for dinner every evening. She has two favourite restaurants, Dosa Paradise and Kababs Unlimited, to which she travels by local train. The train to Dosa Paradise runs every 10 minutes, at 0, 10, 20, 30, 40 and 50 minutes past the hour. The train to Kababs Unlimited runs every 20 minutes, at 8, 28 and 48 minutes past the hour. She reaches the station at a random time between 7:15 pm and 8:15 pm and chooses between the two restaurants based on the next available train. What is the probability that she ends up eating in Kababs Unlimited?

(A) 1/5 

(B) 1/3 

(C) 2/5

(D) 1/2

7Comments
Sumit Verma sumitverma 1 Dec 2016 03:59 pm

If she arrives in the intervals 7:20–7:28, 7:40–7:48, or 8:00–8:08, the next train goes to Kababs Unlimited. This adds up to 24 minutes, out of a total of 60 minutes, so
24/60 = 2/5 .

Jaya jaya1 1 Dec 2016 10:26 pm

I don't understand whts incorrect in this ...for dosa she have 6 options between 7:15 to 8:15 -7:20,7:30 ....8:10 and for kababs unlimited she has 3 options.so probability she ends up eating in Kababs Unlimited is 3/(3+6)=1/3.

karmjit joshi karmjitjoshi 11 Jan 2017 08:33 pm

Train timings for Dosa Paradise

7:20 ,7:30, 7:40, 7:50, 8:00, 8:10

Train timings for Kabab Unlimited.

7:28, 7:48, 8:08

Favourable time slots

7:20-7:28  = 8 minutes
7:40-7:48 = 8 minutes
8:00-8:08 =8 minutes.

Probability= 24/60 = 2/5

priyanka gautam priyankagautam 12 Jan 2017 04:10 pm

why we have taken the time slots here why not 3/9= 1/3 ?

Sujit Chowdhury sujitchowdhury 14 Jan 2017 09:21 am

i also have same doubt ..