SWL9E1: Basic Arithmetic – US Conversions

Here we’re asked to perform a set of single-step conversions. We’re going
to use a conversion from the table write it as a ratio so that our units that were given will cancel, leaving us
with the units that we desire. So let’s see how that’s gonna work. Here we have a relationship between
pounds and ounces we want to convert 4 pounds to ounces. I’m going to look in my table and I’m
going to circle that my conversion is 1 pound is 16
ounces so the long form for working this
problem is to take 4 pounds times, now I’m going to write
my conversion ratio as 16 ounces over 1 pound, so there’s a relationship
between ounces and pounds written as a ratio. I’m
going to put 4 pounds over 1 to remind myself
that this is also a ratio. Now my units of pounds will cancel, I’m going to multiply straight across,
4 times 16 is 64, my units left are ounces, so I can
fill in 64 here. Part B: I want 10 yards converted to a
certain number of feet. So I’m going to look in my table for a conversion here, I see 1-yard is 3-feet. So I’m going to take 10 yards and I’m going to
multiply it times the conversion ratio of 3-feet is 1-yard. So my units will cancel, remember this is really over 1, so I have 10 times 3 is 30, the units I have left are the ones that I want, which are feet. So 10 yards is equivalent to 30 feet. Looking at Part C: I want to convert 2.4 pints to a certain number of cups, and I’m going to look at my
relationship here that 1 pint is two cups. So what I’m going to do here is take 2.4 pints, and I’m going to put that over 1, times my conversion ratio 2 cups to 1 pint. So the units that I want to
cancel are on opposite, top and bottom, 2.4 times 2 gives me 4.8. The units I have left are cups. So I can write that up here. So be sure when you’re working these
problems, when you set up your conversion ratio,
the units that you want to cancel should be
opposite the ones that you start with. So here we cancelled pounds, here we cancelled yards, here we cancelled pints.

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