Thursday, June 11, 2009

A Neat Problem

Recently, I went in for a series of technical interviews in search of a new position. As is typical in an interview for the types of jobs I seek, I was given a few reasoning/logic/brain teaser types of problems. One of them really stumped me, and it was only after being pushed in the right direction that I was able to see the correct approach and arrive at an answer.

Here it is for all of your entertainment.

A man arrives at the train station after work at 5pm daily. His wife always leaves the house earlier to pick him up and she arrives at 5pm sharp every day. After pick up, they head straight home. The commute time each way is always the same, so they get home at the same time each and every day. To be clear, both one-way trips (to and from) take the same amount of time.

One day the man catches the earlier train and arrives at the train station at 4pm. His wife does not know this, and so she is on her normal schedule. The man (at 4pm) decides to start walking home to save his wife some time. The wife sees him on the road on her way to the station. She picks him up and they turn around and head home. They arrive home 10 minutes earlier than their normal arrival time.

For how long did the man walk for?


Corybear said...

55 minutes

Brute Force said...

Ding, ding, ding.

Ya, I really just looked at it the wrong way. My only excuse, I suppose, was that it was the last 20 minutes of a 5-hr session, and so I was tired. Ha ha.

Nice work!

Jimmy said...

Wow. Explain the answer please?

Gary Lo said...

hey dude, I got 55 as well, basically since they arrived home only 10 mins earlier, so effectively the man had only saved the wife 5 mins one way. So supposedly the wife always meet the man at 5pm, it would meant that she met him 5 mins earlier at 4:55 that day and the poor man would have walked 55 mins.

Brute Force said...

Jim -- Gary's explanation is basically the simple and most effective way to look at it. Trust me, I felt pretty dumb not figuring it out without hints.

Jimmy said...

i hate questions where it's not a question of your skill, but of your intelligence, because my INT is low and I suck at them :P