% Tip or Discount
CONCEPTS
Types
• Given a Tax %, Tip % => New amount = Original (1 + %)
• Given a Discount % => New amount = Original (1 - %)
TAX/TIP EXAMPLE
The bill is $20. The tip is 15%. What is the total?
$20 (1 + 0.15) = $20 (1.15) = $23
DISCOUNT EXAMPLE
You buy a car at 10% off. The original price of the car is $15000
$15000 (1 – 10%) = $15000 (1 – 0.10) = $15000 (0.90) = $13500
PRACTICE PROBLEMS
Question 1 A shirt, which costs $20, is on sale at 30% off. What is the sale price?
-- Answer -- $14
$20 (1 – 30%) = $20 - $6 = $14
Question 2 There is a 10% tax on gas in some states. If the original price is $2.50/gallon, what is the price after the gas tax?
-- Answer -- $2.75
$2.50 (1 + 10%) = $2.50 + $0.25 = $2.75
ACT PRACTICE PROBLEMS
