chopped onions

Question

A recipe calls for 1 1/2 gallons of chopped onions. how many pounds of onions should you use it 1 cup of chopped onions weighs 6.5 ounces?

Answer 1

To solve this problem, Meeka, you need to know what the conversion factors are:

 

For volume, 1 gallon = 16 cups.

 

For weight, 1 pound = 16 ounces.

 

So now you can convert 1.5 gallon = 1.5 gallon * 16 cups/ 1 gallon = 24 cups.

 

So you need to chop 24 cups of onions (better wear your ski googles!), and each cup weights 6.5 ounces, so the total weight of onions is

 

weight = 24 cups * 6.5 ounces / 1 cup = 156 ounces.

 

Now we can convert this weight back into pounds:

 

weight = 156 ounces * 1 pound / 16 ounces = 9.75 pounds.  That's a lot of onions!..

 

Always write your ratios with units and make sure the units cancel out from the numerator and denominator.  That way you know you applied the conversion factors the right way.

 

Now try to solve the problem in a more systematic, faster way, like this:

 

weight = 1.5 gallon * (16 cups/ 1 gallon) * (6.5 ounces / 1 cup) * (1 pound / 16 ounces)

          = 1.5 * 16 * 6.5 / 16 pounds

          = 1.5 * 6.5 pounds = 9.75 pounds.

 

Hope this helps. 

 

Jean-Michel