Video Transcript
Divide 72 centimeters in the ratio
two to three to one.
Let’s recall one of the methods we
have for sharing into a ratio. It’s called the add-divide-multiply
method. In this method, the first thing we
do is we add the numbers in our ratio. This will tell us the total number
of parts we’re sharing into. Our ratio is two to three to
one. And two plus three plus one is
six. So we have a total of six
parts.
Step two is to divide the amount
we’ve been given by this number. This will tell us what one part is
worth. We’re dividing 72 then by six, and
that gives us 12. Of course, we’re actually working
in centimeters. So we can say that one part is
worth 12 centimeters.
Our final step is to multiply each
bit of the ratio by this number. Essentially, if we know the value
of one part, we can find the value of two by timesing it by two, we can find the
value of three by timesing it by three, and so on. Two multiplied by 12 is 24, so the
first bit we get is 24 centimeters. Three times 12 is 36, so our second
bit is 36 centimeters. Then one multiplied by 12, which we
don’t really need to do but we’ll do for completion, is 12. And the third bit is 12
centimeters.
When we divide 72 centimeters in
the ratio two to three to one, we get 24 centimeters, 36 centimeters, and 12
centimeters. In fact, 24 plus 36 plus 12 gives
us the original 72 as we required. So we know that we’ve probably done
this correctly.
