Carpentry & Building Construction © 2004

Math Activities :

Self-Check Math Activity 13

Converting Percents to Fractions

Carpenters may need to change percents to fractions in order to perform calculations. To convert a percent to a common fraction, first write the percent as a decimal. Next change the decimal to a fraction. The final step is to reduce the fraction to lowest terms.

Terms, Symbols, & Abbreviations
common fraction - a fraction in lowest terms
lowest terms - describes a fraction in which the numerator and denominator cannot be divided by a common number

Practice Exercise

Convert 7.75% to a common fraction.
Step 1	Write the percent as a decimal.
	7.75% = .0775
Step 2	Change the decimal to a fraction.
	.0775 = 775/10000
Step 3	Reduce the fraction to lowest terms.
	775/10000 = 31/400

Problem Exercises


1.	Convert 62.5% to a common fraction. Use lowest terms.
		A)	125/2
		B)	125/20
		C)	5/16
		D)	5/8


2.	Convert 16.8% to a common fraction. Use lowest terms.
		A)	21/125
		B)	21/100
		C)	84/50
		D)	125/21


3.	The waste allowance for a job is 20%. What is the common fraction for this allowance?
		A)	20/10
		B)	20/1
		C)	1/5
		D)	2/5


4.	The overtime pay rate for a job is 150%. What is the common fraction for this rate?
		A)	15/1
		B)	3/2
		C)	2/3
		D)	1/2


5.	A builder gets a price quote for lumber that is 35% higher than last year. Express the percent increase as a common fraction.
		A)	35/10
		B)	7/10
		C)	7/20
		D)	5/20