Ratio, Proportion, Percent –
Reference: K. Elayn MartinGay – Page 1 Definition: Ratio / Proportion
Ratio Comparison of Two numbers Symbols of Comparison: / to : 2/3 2 to3 2:3 4/7 4 to 7 4:7 
Problem SolvingUnderstand the Problem Translate the Problem Solve the Problem Check the Problem The ratio of boys to girls on a team is 5 to 7. If the team has 35 members then how many boys and girls? 
ProportionTwo Equal Ratios or Fractions2/3 = 4/6 3 to 4 = 9 to 12 3 : 5 = 12 : 20 
The Law of ProportionsProduct of Extremes = Product of Means2/3 = 4/6 2x6 = 3x4 3 to 4 = 9 to12 3x12 = 4x9 3 : 5 = 12:20 3x20 = 5x12 
Percent means Part of 100Percent to Fraction8% = 8/100 17% = 17/100 240% = 2 2/5 
Percent means Part of 100Percent to Decimal7 % = .07 15% = .15 135% = 1.35 
Percent Problem25% of N = 4 25/100 = 4 / N 25N = 400 N = 16 What about? N% of 10 is 5 
Percent Problem40% of 20 is N 40/100 = N /20 800 = 100N 8 = N What about? N% of 3 is 12 
Thomas Love Malone College 2006/2008
Ratio, Proportion, Percent –
Reference: K. Elayn MartinGay – Page 2 Definition: Ratio / Proportion
Percent of Increase A score was increased from 60 to 80. What percent of increase? 60 is increased 20 to be 80 Amount increased
over original number! 20 / 60 = N / 100 
Percent of DecreaseA price was decreased from $5 to $4. What percent of decrease? $5 is decreased $1 to be $4 Amount of decreased
over original number! 1 / 5 = N /100 
Commission or TipFifteen Percent is considered to be a good commission or tip! Sales of $200 expects a commission or tip of how much? 15% of $200 is N 15/100 = N/200 N = $30 A good commission & tip! 
Discount or

Simple InterestInterest = Principal x Rate x Time P = $2000 R = 3% T = 4 years I = 2000 x .03 x 4 I = $240 
Savings AccountSavings = Principal + Interest P = $400 R = 6% T= 5 years I = 400 x .06 x 5 = $120 Savings = $400 + $120 = $520 
Direct Relation A Direct Relation between two variables is such when one goes down then
the other goes down or when one goes up then the other goes up. All other variables remain unchanged! The quotient
of the two variables is a constant! V1 72
48 36 18
12 6 V2 24 16
12 6 4 2 
Inverse Relation A Inverse Relation between two variables is such when one goes down then
the other goes up or when one goes up then the other goes down. All other variables remain unchanged! The product
of the two variables is a constant! V1 36
24 18 12 6 3 V2 2
3 4
6 12 24 
Thomas Love Malone College 2006/2008