The Morgan silver dollar has a mass of 26.73g. By law it is required to contain 90% silver, with the remainder being copper. (A) When the coin was minted in the 1800s, silver was worth $1.81 per troy ounce (31.1g). At this price what is the value of silver in the silver dollar? (B) Today, silver sells for about $5.30 per troy ounce. How many Morgan silver dollars are required to obtain $25.00 worth of pure silver?

2A. When it was first minted in 1800s, silver was worth $1.18 per troy ounce (31.1g). At this price, what is the value of the silver in the silver dollar?

WHAT YOU KNOW

• Silver dollar has a mass of 26.73g.
• It is required to contain 90% silver.
• Silver at the time was worth $1.18/ troy ounce
• One troy ounce is 31.1g

Step One:
26.73g x 0.9= 24.057g

Step Two
24.06g x 1 troy ounce/31.1g =
.7736 troy ounces

Step Three
$1.18 x .7736= $0.91*

*sigfigs to the 100th because you are working with a dollar value

2B. Today silver sells for $5.30 per Troy ounce. How many Morgan silver dollars are required to obtain $25.00 worth of pure silver?

WHAT YOU KNOW

• There are .7736 troy ounces of silver in a Morgan silver dollar.
• The price of silver today is $5.30.
• You need to reach $25.00 of pure silver.

Step One
.7736 troy ounces x $5.30 = $4.10 per silver dollar

$25.00 = $4.10(x)
(x)=6.098 silver dollars

Why not 6 silver dollars?
(x)=6.098

6($4.10)= $24.60
vs
7($4.10)= $28.70