we have already drawn one black card, that changes our numerator and
denominator.
Finally, we just multiply our two events together, then reduce our fraction to the
lowest whole numbers:
Percentages
Percentages are fraction problems in disguise because percent means per
hundred. So 25% can also be read as ^25 / 100 . So if I ask for “25% of y,” I am
asking for ^25 / 100 or if you’re using a calculator: .25 × y.
We do the same thing for percentages greater than 100%. For instance, 250%
means ^250 / 100 or 2.5.
But there are more difficult percent questions, such as:13 is 20% of what number?Here we can set up an equivalency, like this:
Let’s plug in our numbers. Be careful! Is 13 the part or the whole? If we are
saying that 13 is a percent of another number, it must be the part.
Cross multiply to find that our whole is 65.
Whenever I see a percent, I automatically think of the fraction it represents. 20% = just multiply 13 × 5 and— voilà—65.^20 / 100 = ^1 / 5 . So, to solve 13 is ^1 / 5 of what number, you
—SamanthaPERCENT INCREASE AND DECREASE