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Maths homework - please help!

(8 Posts)
marthamoo Wed 24-May-06 15:26:38

It's only one question but it's making my head hurt...

Ram divides 15 pennies among four small bags.

He could then pay any sum of money from 1p to 15p, without opening any bag.

How many pennies did Ram put in each bag?

Is there some really obvious way of working this out or is it trial and error?

jessicaandrebeccasmummy Wed 24-May-06 15:27:51

im confused by the question!!!

marthamoo Wed 24-May-06 15:31:09

I was at first - I thought it was one of those logic puzzles - like, how can he pay out the money without opening the bags? Answer: he landed in the middle of the field and he had no parachute.

But I think it means you can put x amount of pennies in each bag and then give one or a combination of the bags to make any amount between 1 and 15p.

calicopie Wed 24-May-06 15:31:32

You'd have to divide up like this:

1p in one
2p in second
4p in 3rd
8p in 4th
Then you can get all combinations up to 15p.

e.g. to get 9p you'd use 8p bag and 1p bag etc.

SaintGeorge Wed 24-May-06 15:32:03

What calicopie said - saves me typing it out

Bink Wed 24-May-06 15:32:11

It's about triangular numbers, isn't it? - numbers that aggregate to make other numbers?

So the answer is:
- bag 1 must have one penny in it;
- bag 2 must have two pennies in it;
- bag 3 must have four pennies in it;
- bag 4 must have eight pennies in it.

So to pay 1p you hand over bag 1, to pay 2p you hand over bag 2, to pay 3p you hand over bags 1 + 2, to pay 4p you hand over bag 3, to pay 5p you hand over bags 3 + 1 ... etc.

jessicaandrebeccasmummy Wed 24-May-06 15:33:18

ive got it now!!!

marthamoo Wed 24-May-06 15:39:02

Thanks guys. I've never heard of 'triangular numbers'. Ds1 said "Mum, I don't get it," so I looked and I said "I don't get it either...but I know a bunch of women who will ."

Thanks guys, will sit and help him work it out now I know what I'm doing.

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