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St Joseph's College Lucan

Maths Week Solutions!

22-October-19
Maths Week Solutions!

Our Maths Department would like to thank everybody who entered the Maths Week Daily Quiz. The Solutions are here!

Tuesday’s Maths Week Puzzle

Tom asked his Granny how old she was - she replied:
"I have 6 children, and there are 4 years between each one and the next. I had my first child (your Uncle Peter) when I was 19. Now the youngest one (your Auntie Jane) is 19 herself.’ How old is Tom’s Granny?

Solution:

Tom's Granny is 58 years old.
First child born: Granny is 19
Second child born: Granny is 23 (19 + 4)
Third child born: Granny is 27 (23 + 4)
Fourth child born: Granny is 31 (27 + 4)
Fifth child born: Granny is 35 (31 + 4)
Sixth child born: Granny is 39 (35 + 4)
Sixth child is 19: Granny is 58 (39 + 19)

Wednesday’s Maths Week Puzzle

Suppose you want to boil an egg for exactly 9 minutes.
You have two hourglass egg timers, one measures 7-minutes, and the other measures 4-minutes. How can you correctly measure 9 minutes?

Solution:

Put the egg on to boil and start both hourglasses running. When the 4-minute one runs out, turn it over immediately so it starts counting 4-minutes again. When the 7-minute one runs out, turn it over so it starts counting again.
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. Let the sand run back again (1 minute more) and then take the eggs off straight away, because they will have boiled for 9 minutes. (4 minutes twice, plus one more minute = 9 minutes!)

Thursday’s Maths Week Puzzle

Can you draw a diagram to show how you would use exactly SIX straight lines to make FOUR identical triangles?

Solution:

Screenshot 2019-10-22 at 08.14.48.png

Friday’s Maths Week Puzzle

Three days ago, yesterday was the day before Sunday. What day will it be tomorrow?

Solution:

That means today is Wednesday, so tomorrow is Thursday

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