What's $1 Really Worth?

Have you ever wondered what the value of the metal used to make a coin is?
The Australian $1 coin has a mass of 9 grams and is composed of:

• 92% copper
• 6% aluminium
• 2% nickel

 If we convert each percentage to a mass, then the Australian $1 coin is composed of:

• 92/100 x 9 = 8.28 g of copper
• 6/100 x 9 = 0.54 g of aluminium
• 2/100 x 9 = 0.18 g of nickel

The following are the approximate costs per tonne for each metal:

• copper: $ 7000 per tonne
• aluminium: $ 1750 per tonne
• nickel: $ 19 000 per tonne

Now we convert the cost of each metal per tonne to a cost per gram:

• copper: $7000/1000 = $7 per kg = 7/1000 = $0.007 per gram = 0.7 cents per gram
• aluminium: $1750/1000 = $1.75 per kg = 1.75/1000 = $0.00175 per gram = 0.175 cents per gram
• nickel: $19000/1000 = $19 per kg = 19/1000 = $0.019 per gram = 1.9 cents per gram

Then calculate the value of each of metal used to make an Australian $1 coin:

• copper: 8.28 g x 0.7 cents per gram = 5.796 cents
• aluminium: 0.54 g x 0.175 cents per gram = 0.0945 cents
• nickel: 0.18 g x 1.9 cents per gram = 0.342 cents

The value of an Australian $1 coin is
5.796 cents + 0.0945 cents + 0.342 cents = 6.2325 cents!

Further Reading:
Percentage Composition Calculations
Mass Conversions

Calculate the value of each of the following coins:

1. Australian $2 coin has a mass of 6.60 g and is composed of  92% copper, 6% aluminium, 2% nickel
2. Australian 50 cent coin has a mass of 15.55 grams and is composed of 75% copper, 25% nickel
3. Australian 20 cent coin has a mass of 11.31 grams and is composed of 75% copper, 25% nickel
4. Australian 10 cent coin has a mass of 5.66 grams and is composed of 75% copper, 25% nickel
5. Australian 5 cent coin has a mass of 2.83 grams and is composed of 75% copper, 25% nickel
6. An American nickel (5 cent coin) has a mass of 5.00 grams and is composed of 75% copper, 25% nickel
7. An American dime (10 cent coin) has a mass of 2.268 grams and is composed of 91.67% copper, 8.33% nickel
8. An American quarter (25 cent coin) has a mass of 5.67 grams and is composed of 91.67% copper, 8.33% nickel