Jim paid $3.99 for a 14-ounce bag of cookies. What was the
unit cost per pound?
$3.99 / (14/16 lb) = (8/7)*($3.99) = $4.56/lb
More than one way to skin a cat. Proportions come up a lot and this can be solved as one.
State the relationship you need verbally.
"3.99 is to 14, as x is to 16"
Then set up a proportion.
3.99 x
---- = ----
14 16
Cross-multiply, giving:
14x = 16(3.99)
Divide both sides by 14, giving:
x = (16/14)3.99
Reduce:
x = (8/7)3.99
Finally, you need to pull out your calculator.
x = 31.92/7
x = 4.56
That is the cost per 16 ounces: that is, per pound.
To find the unit cost per pound, we need to convert the cost from per ounce to per pound.
First, let's convert the cost to per pound.
There are 16 ounces in a pound, so the cost per pound is:
$3.99 / 14 ounces * 16 ounces per pound = $3.99 / 14 * 16 = $3.99 / 224 = $0.0178 per ounce
Now, let's convert the cost per ounce to cost per pound.
To convert ounces to pounds, we divide the cost per ounce by 16:
$0.0178 per ounce / 16 ounces per pound = $0.0011 per pound
So, the unit cost per pound is $0.0011.