Ratio, Proportion, Percent – Basic College Mathematics for Teachers

Reference: K. Elayn Martin-Gay – 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 Solving Understand 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?
Proportion Two Equal Ratios or Fractions 2/3 = 4/6 3 to 4 = 9 to 12 3 : 5 = 12 : 20	The Law of Proportions Product of Extremes = Product of Means 2/3 = 4/6 2x6 = 3x4 3 to 4 = 9 to12 3x12 = 4x9 3 : 5 = 12:20 3x20 = 5x12
Percent means Part of 100 Percent to Fraction 8% = 8/100 17% = 17/100 240% = 2 2/5	Percent means Part of 100 Percent to Decimal 7 % = .07 15% = .15 135% = 1.35
Percent Problem 25% of N = 4 25/100 = 4 / N 25N = 400 N = 16 What about? N% of 10 is 5	Percent Problem 40% 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 – Basic College Mathematics for Teachers

Reference: K. Elayn Martin-Gay – 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 Decrease A 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 Tip Fifteen 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 Sale Price An item is Discounted or has a Sale Price lower then original. An original Price of $35 is discounted 20%. What is amount of discount & sale price? 20% of $35 is N 20/100 = N/35 Discount = $7 & Sale Price = $28
Simple Interest Interest = Principal x Rate x Time P = $2000 R = 3% T = 4 years I = 2000 x .03 x 4 I = $240	Savings Account Savings = 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