How do you measure 15 minutes to boil an egg if there are 2 kinds of hourglass?

So basically you can do the following:

1. Start both hourglasses.
2. When the 7-minute one is finished, flip it over.
3. When the 11-minite one finished, flip the 7-minute one over.
4. When the 7-minute one is finished, it is 15 minutes!

How do you make a 9 minute egg if all you have is a 4 minute and 7 minute egg timer?

When the 4-min timer is empty for the second time, the 7-min timer has 1 minute worth of sand in the bottom half. Flip it over so there is now 1 minute in the top. When the 7-min timer empties, 9 minutes have elapsed.

Can you boil egg for 15 minutes?

Fill pot with water to completely cover the eggs at least 1 inch above eggs and turn heat to high. Bring water to a boil, takes approximately 15 minutes. As soon as eggs start to boil, let boil for 10-12 minutes (I do 11 minutes). Keep hard boiled eggs in their shell in the refrigerator for up to 1 week.

How are sand timers made?

Its design was simple. Two globes (also called phials or ampules) of glass were connected by a narrow throat so that sand (with relatively uniform grain size) flowed from the upper globe to the lower. Hourglasses were made in different sizes based on pretested measurements of sand flow in different sizes of globes.

How do you make a 9 minute egg?

Add water to your pot, keeping in mind that you only need enough to cover the eggs, and bring to a boil. Once you’re boiling, turn off the heat, add the eggs, cover and start your timer for nine minutes. A nine minute cook time is best for large eggs.

How do you fix an egg timer?

Our Solution: Put the eggs on to boil and start both hourglasses running. The moment the 4-minute one runs out for the second time, turn the 7 minute hourglass over – it will have only been running exactly one minute.

How do you use two Sand timers?

Originally Answered: You have two sand timers, which can show 4 minutes and 7 minutes respectively. Use both the sand timers (at a time or one after other or any other combination) and measure a time of 9 minutes? Turn over the four-minute timer. When it is half empty, flip over the seven-minute timer.

How long does it take to empty the sand?

This Puzzle is one of the most commonly asked interview puzzle. Problem: You have two sand timers with you. One can measure 7 minutes and the other sand timer can measure 11 minutes. This means that it takes 7 minutes for the sand timer to completely empty the sand from one portion to the other. You have to measure 15 minutes using both the timers.

How do you count to 9 minutes on a 7 minute timer?

When the 7 minute timer is done, the 4 minute timer will have 1 minute left. Now you can count to 9 minutes by simply leaving the 4 minute to expire (1 min), flip it and let it expire (4 min), flip it again and let it expire (4 min). 1 + 4 + 4 = 9 The key is understanding that you will have to use the two hourglasses together.

How to use 4m timer and 7m timer?

Start both the timers at a time. Filp over 4 m timer twise & so that when 7m timer is over , flip it . There is sand remaining in 4m timer for one minute. Start 7m timer and when one minute sand in 4m timer is over mark that point on 7m timer.