7th Grade Math

334 Percent

Find the Whole

18 is 25% of what number?

Words

Variable

Proportion

18 is 25% of what number?

Let w represent the whole.

part

whole (^18) w = 10025 percent
^18
w
= ^25
100
Write the proportion.
18 · 100 = w · 25 Find the cross products.
1,800 = 25 w Simplify.
1,800

25
= _^25 w
25
Divide each side by 25.
72 = w
So, 18 is 25% of 72.
e. 40% of what number is 26? f. 84 is 75% of what number?
ANIMALS The average adult male Western Lowland
Gorilla’s Diet
Food Percent
Fruit 67%
Seeds, leaves,
stems, and pith 17%
Insects/
insect larvae 16%
Western Lowland gorilla eats about
33.5 pounds of fruit each day. How
much food does the average adult
male gorilla eat each day?
You know that 33.5 pounds is the part.
You need to find the whole.
33.5
w
= ^67
100
Write the proportion.
33.5 · 100 = w · 67 Find the cross products.
3,350 = 67 w Simplify.
3,350

67
= ^67 w
67
Divide each side by 67.
50 = w
The average adult male gorilla eats 50 pounds of food each day.
g. ZOO If 200 of the 550 reptiles in a zoo are on display, what percent
of the reptiles are on display? Round to the nearest whole number.
Real-World Link
Male Western
Lowland gorillas
weigh about
350–400 pounds.
Females weigh about
160–200 pounds.
RR
M
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