Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

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

ran
Member
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?

Offline

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

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,393

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.

Bob


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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,676

Re: coins problem

Hi;

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.

Offline

Board footer

Powered by FluxBB