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#1 2013-06-03 04:32:06

Registered: 2013-06-03
Posts: 1

coins problem

Hi hopefully you guys can help me with this problem sum.

there are 45 coins in the piggy bank.

total amount is $21.90

there are 7 $1 coins in the piggy bank.

how many $0.50 and $0.20 coins are there in the piggy bank?


#2 2013-06-03 06:09:20

bob bundy
Registered: 2010-06-20
Posts: 6,395

Re: coins problem

hi ran,

Welcome to the forum.

I've made two equations from this information and tried to solve the problem.  But the number of $0.50 coins has come out as a fraction so either I've made a silly error or the information has a typo.  Have a look and see if you can sort it out;  the method should work.

First some letters for the number of coins.  I'm from the UK so I couldn't remember what you call those coins so for $0.50 I'm using H and for $0.20 I'm using F.

First equation based on number of coins

Second based on value of coins

Multiply the first by 2 and subtract the result from the second

Now if 73 was in the 3x table that would give H and F would quickly follow.  But you cannot have H not a whole number so I'm stuck.


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei


#3 2013-06-03 22:55:35

From: Bumpkinland
Registered: 2009-04-12
Posts: 86,776

Re: coins problem


There are no integer solutions to that problem.

I think the problem is a typo. Now  total amount is $21.80 has a solution.

In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.


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