Here's an interesting interview question I thought of on my way home from a party recently.
- You are parked at some starting point
SPwhich is between 2 exits
E1 and E2
- We were at a cross road with Road 1
- Our starting point is set between exit 1 and exit 2 on the highway
E1 and E2of road 2
- To reach our destination we must reach exit 4
E4which is past
- Speed limit of
R2= 50 (double)
??? When will going to E1 be faster ???
SP at which distance is it faster to go back to
E1 instead of going forward to
D1 = D3 - D2(i.e. D2 is always a shorter distance)
D1both have the same speed (
D3is double ( or .5 the distance )
R2is 2x the speed of
R1it will take half as long to travel
S1is closer than half way then
D1will always be faster than
D3alone. Meaning the faster route is determined before the car arrives at
- In the same vein, for
E1to be faster the car needs to arrive before it would have reached
1/2 * D3)
- Since they travel at the same speed if
S1if 1/4 of the way between
E2, and it would reach
E1at the same time that it would reach
1/2 * D3(i.e.
< 1/4 of D3)
Its about how the interviewee answers the question, not the answer they give.
So, take note of the interviewees thought process while solving the problem.
Remember: The question is better when you word it like I did.
Do not say Which route is faster.
That is not the question, it is When is going backward faster.
This will force the interviewee to use a logical thought instead of a geometrical.