Math Fair 2012
_Imagine a country that has only two denominations of currency: $7 bills and $11 bills. How would the economy work in this country?
You may answer any or all of the questions below. Quality and quantity are both important.
You may answer any or all of the questions below. Quality and quantity are both important.
Part 1
With only $7 and $11 bills available, it is impossible to make a stack of money worth exactly $3. It is also impossible to make a stack worth $15. However it is possible to make a stack of money worth $25 by using two $7 bills and one $11 bill. (2 * 7 + 11 = 25)

Part 2
There are two different ways to make $120. For example, you can use three $7 bills and nine $11 bills (3*7 + 9*11 = 120) or you can use fourteen $7 bills and two $11 bills (14*7 + 2*11 = 120)

Part 3
Although it is impossible to make a pile of money worth exactly $3, it is still possible to buy something that costs $3. You can give two $7 bills to the cashier and receive one $11 bill as change. (2*7  11 = 3)

Part 4
Imagine that a $20 bill has been added to the money supply.
