A)
B)
C) 18
D) 54
Translate!
Direct means divide.
Since inverse
is the opposite, inverse means multiply.Here’s How to Crack It
For inverse proportions, follow the formula. First, convert the days: 3 days is equal to 72 hours. Now set
up the equation: (12 vultures)(72 hours) = (16 vultures)(x). We solve to get x = 54, which is 18 fewer
hours. The answer is (C).
Since ratios and proportions are related concepts, you might be wondering how you can tell when you
should set the problem up as a proportion and when you should use a Ratio Box. Here are some
guidelines to help you decide.
- If the question gives you a ratio and an actual number, use a Ratio Box.
- If the question compares items that have different units (like feet and seconds), set up a
proportion. - If you don’t need the total column in the Ratio Box, then you can also do the question by setting
up a proportion.
PERCENTAGES
Percentages Are Fractions
There should be nothing frightening about a percentage. It’s just a convenient way of expressing a fraction
whose bottom is 100.
Percent means “per 100” or “out of 100.” If there are 100 questions on your math test and you answer 50
of them, you will have answered 50 out of 100, or , or 50 percent. To think of it another way:
= x percent