Use Percentages Math Skills LESSON 2

Name
Date
Math Skills
Class
LESSON 2
Use Percentages
A percentage compares a partial amount to a whole amount. A whole amount is equal to
100%. To calculate percentage, change a ratio to a decimal, multiply by 100, and then add
1 is equal to 0.25 and to 25%.
a percent symbol. For example, __
4
The kidneys filter 180 L of plasma each day. If 1.3 L of urine are produced during one day,
what percentage of the filtered plasma is excreted as urine?
Step 1 Identify the ratio and write it as a fraction. The numerator of the ratio represents
the partial amount, and the denominator represents the whole amount.
1.3
____
180
Step 2 Divide to change the ratio to a decimal.
1.3
____
= 1.3 ÷ 180 = 0.007
180
Step 3 Multiply by 100 and add the percent symbol.
0.007 × 100 = 0.7%
Practice
1. The kidneys filter 180 L of plasma
2. The total length of the intestines is
approximately 8.5 m. Sam had minor
surgery to remove 0.4 m of the intestine.
What percentage of the intestines was
removed?
36
intestine, and the entire process of
digestion takes 57 hours. What
percentage of the total digestion time
does food spend in the small intestine?
4. Food spends 4 hours in the small
intestine and 48 hours in the large
intestine. The entire process of digestion
takes 57 hours. What percentage of
the total digestion time does food spend
in the small and large intestines
combined?
Digestion and Excretion
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
each day. If 1.9 L of urine are produced
during one day, what percentage of
the filtered plasma is excreted as urine?
3. Food spends 4 hours in the small