Question
You were provided with two strings. The only thing you know about that string is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.
So, the question is How would you measure 45 minutes with this information?
Solution
Take both the strings, light the 1st string on both ends and on the 2nd string, light it only on one end. By this, when the 1st string gets completely burnt, it exhibits the completion of 30 minutes, and on the same time the 2nd string gets burnt half.
When the 1st string gets burnt completely, light on the another end of the 2nd string. Doing this when the second string burnts completely, it completes a total of 45 minutes for the entire procedure.
1st string burnt completely = 2nd string burnt half = 30 minutes
At this time the 2nd string remains half
2nd string burnt completely = 15 minutes
Total of 45 minutes
Some people have difficulty grasping that when you light both ends of the first fuse, it will take 30 minutes to burn. Because the burning rate is random and unknown to you, you have no idea where the 30 minute mark is on the fuse. If you had an exact duplicate, then the 30 minute mark would be in the same place. It is probably not in the middle, but it is somewhere. If you burn both ends of a fuse it will not stop burning until it has reached this mark, which means 30 minutes is up.
Please share your thoughts in the comments.
No comments:
Post a Comment