It’s a fun puzzle to see how you can achieve a result in the most creative way with the least material.
Let’s see if you can solve this question and prove that you have a higher-than-average intelligence.
From the hourglass in the image, you can measure 11 minutes with the one on the left and 7 minutes with the one on the right. How can you use these two hours to measure 15 minutes?
Let us remind you that there are two solutions to the problem.
Think a bit before jumping into the answer, because the solution is pretty fun too.
Now let’s get to the answer:
Here’s the first method: Turn them both over at the same time. After the 7-minute hourglass ends, 4 minutes later, the 11-minute hourglass will also end. When this is done, turn it over immediately. Now you will measure 11 minutes, previously you measured 4 minutes. In this way, you can manage to measure 15 minutes in total.
There is a problem with this method, you had to spend 22 minutes to solve the 15 minutes (since you had to turn the hourglass twice, which took 11 minutes).
However, there is a better method where you can solve 15 minutes in 15 minutes. Can you find it?
If you can solve the first question, you have an above average intelligence. You need to be more creative with this answer. Let’s see if you are above average intelligence?
Now let’s take a look at the other solution method:
- As in the previous solution, you have to dial both clocks at the same time.
- When the 7-minute clock is over, turn it over again immediately.
- 4 minutes after turning it over, the 11-minute clock ends (You’ve measured 11 minutes so far).
- When the 11-minute clock runs out, turn the 7-minute clock, even though it’s unfinished. Thus, 3 minutes of sand remains.
- Dial the 7-minute clock again. This leaves 4 minutes of sand on the top. When this time is over, you will have measured 11+4=15 minutes.
Who solved it?
Sources: Popular Mechanics, Mathematical
12289
