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Wednesday: Miss Marydoll’s, Eggciting Eggcellent, Eggsasperating, Eggceptional, Egg Puzzle.

(35 Posts)
Marydoll Wed 15-Apr-20 09:17:55

Good morning all you eggceptional mathematicians, here is today's puzzle.
If you click on the image, it will be easier to see.

How can you boil an egg for exactly nine minutes with only a 4-minute hourglass and a 7-minute hourglass to measure the time?

willa45 Wed 15-Apr-20 18:14:41

Willa's late,
They locked the gate
She didn't run
and missed the fun,
but here's her homework...no harm done

Nine minute eggs

Start both timers at the same time (Call the 7 min, 'Big' and the 4 min, 'Little').

After 4 min, Big has 3 min of sand left and Little is at zero. so we must flip Little a second time.

After 3 min, Big is now at zero and there's still 1 minute left in Little. (7 minutes have elapsed) Flip Big.

While (eight) minute from Little elapses, Big is dropping its own minute of sand on the bottom. and has 6 minutes of sand remaining on top ( at this point, 8 minutes have elapsed).

Flip Big so that 1 min of sand is now on top and the other six on the bottom. Now you can measure your extra minute and that's how you get to minute 9.

Doodle Wed 15-Apr-20 19:08:35

pantglas and willa thanks for joining in. Butter wouldn’t melt pantglas oh yeah ?

Doodle Wed 15-Apr-20 19:10:31

willa’s late but never fear
It always more fun when she is here
She lives in a land far away
So it takes her longer to get here and play?

Marydoll Wed 15-Apr-20 19:35:42

Thank goodness, Willa has arrived, better late than never!

Bathsheba and Wila, spot on. ? for you.
Doodle ? for your poem.
Callistemon ?for initiative.

For my other favourite pupils. Pantglas, Gillybob and Feelingmyage, ? for being such good sports.

Here was the solution, I was going to post, before the others beat me too it.

ANSWER: Drop the egg in the boiling water and flip both hourglasses over. When the 4-minute hourglass runs out, flip it over. When the 7-minute hourglass runs out, flip it over as well. Now there is one minute left in the 4-minute hourglass. When it runs out, 8 minutes will have elapsed and there will be 6 minutes left in the 7-minute hourglass. Flip over the 7-minute hourglass again. A minute later the 7-minute hourglass will run out and a total of 9 minutes will have elapsed.

PS:, I'm not sharing my chocolate stash, Doodle. wink

Callistemon Wed 15-Apr-20 19:38:22

Thank you MissMary

My head was beginning to hurt

Callistemon Wed 15-Apr-20 19:39:38

Ooh, I got a star for Initiative

I'm always full of initiative, which means I am usually off piste.

Doodle Wed 15-Apr-20 20:29:18

Oh miss I’ve never had a star before ? mind you I would have preferred the chocolate ?

Marydoll Wed 15-Apr-20 20:36:19

Too late, I ate it!

Doodle Wed 15-Apr-20 20:37:00

Oh ?