Hour glass problem : How can you calculate 9 minutes?
You are given two hour glasses
They can measure
4 and 7 min respectively.
Now you have to calculate 9 min
using these two hour glass
Note : you have to calculate it at a stretch
To see the answer of this puzzle, please click on any social icons below. Sometime you may need to refresh the page to see them properly.
Answer of the puzzle How can you calculate 9 minutes is :
To get 9 minutes first let both the glasses run together. After 4 minutes first glass (4 minute) will be empty so turn/revers that and let it run again. At this point of time second glass (7 minutes) will still be running.
After 3 minutes (total minutes measured so far is 7) second glass will be empty. Now turn/reverse that again and let it run.
After another 1 minute (total minutes measured so far is 8) once again first glass will be empty but the crux here is second glass has only run for 1 minute. What you need to do is immediately turn/reverse the second glass. The second glass will run for another 1 minute and that will be your total 9 minutes.
If you have another easy method do share in the comment section.
Only a smart person can solve following challenging puzzles!!