Equivalent Ratios in the Real World 1-6
There are 2 ways
to determine if 2 ratios are equivalent:
1. Restate them
both as unit rates. If they’re the same unit rates, they’re equivalent.
2. Use equivalent
fractions if finding the unit rate is difficult (let’s say you need to go
several decimal places in the division and don’t have a calculator)
Example using both
methods:
You know that one
store will charge you $2 for 10 photo prints and another has a sign offering 30
prints for $6.
Are these 2 stores
charging EQUIVALENT AMOUNTS?
First way: Unit
Rates
The unit rates are
the same:
You can either
find the prints per dollar or the unit price per print.
Prints per dollar:
10 prints/$2 = 5
prints/$1 and 30 prints/$6 = 5 prints/$1 as well
Unit price:
$2/10 prints =
$.20/print and $6/30 prints = $.20/print as well
Second way:
Equivalent Fractions
The equivalent
fraction approach asks you to see if you can find a common factor that the
numerator and denominator were both either multiplied by or divided by to get
to each other:
Can I get from
10/2 to 30/6 by multiplied both the numerator and denominator by the same
number?
Yes I can!
I can multiply by
3 (scale forward by 3)
When I do this,
it’s helpful to show a curved arrow with the x 3 on each arrow:
So by using
equivalent fractions, the 2 stores are offering the same deal.
