1. © A Very Good Teacher 2008 8 th Grade TAKS Review 2008 Objective 2 Day 1

2. © A Very Good Teacher 2008 Rates Rates can be expressed as: Speed (miles per hour) Cost (Price per pound) Cost per Item To determine the rate: Divide Example: 100 miles in 2 hours 100 ÷ 2 50 miles per hour Obj. 2: 8.3A

3. © A Very Good Teacher 2008 Comparing Rates Example: Store #1 sells a 12 ounce soda for $1.29 and Store #2 sells a 16 ounce soda for $1.80. Which store has the best deal? Obj. 2: 8.3A Determine the rate for each store (cost per ounce) Store #1 $1.29 ÷ 12 =$1.80 ÷ 16 = $0.1075 per ounce$0.1125 per ounce This is the best deal because it is the lowest cost per ounce!

4. © A Very Good Teacher 2008 Comparing Rates, cont… Example: A pet store sells an 8-pound bag of dog food for $6.48. Which of the following represents the same price per pound? A. A 20-pound bag for $24.69 B. A 15-pound bag for $12.15 C. A 10-pound bag for $8.48 D. A 5-pound bag for $3.48 Price per pound: $6.48 ÷ 8 =$0.81 $24.69 ÷ 20 =$1.2345 $12.15 ÷ 15 =$0.81 $8.48 ÷ 10 =$0.848 $3.48 ÷ 5 =$0.696 Obj. 2: 8.3A

5. © A Very Good Teacher 2008 Sales Tax Sales tax is always added to the original price of the item To find the sales tax multiply the tax rate by the original price Example: If a pair of shoes cost $19.99 and the tax rate is 8.5%, what is the total cost of the shoes? Obj. 2: 8.3B Original Price + Tax = Total Cost 19.99 +.085(19.99) = Total Cost 19.99 + 1.69915 = Total Cost $21.69 = Total Cost = 0.085

6. © A Very Good Teacher 2008 Sales Tax, Cont… Example: Carmen bought 3 books for $51.57. If each book cost $15.99 before tax was added, what tax rate did she pay? A. 1.2% B. 3.6% C. 8.5% D. 7.5% Obj. 2: 8.3B Original Price + Tax = Total Cost 3(15.99) + tax(original price) = 51.57 47.97 + tax(47.97) = 51.57 -47.97 tax(47.97) = 3.60 47.97 47.97 tax = 0.075

7. © A Very Good Teacher 2008 Sales Tax, Cont… Example: Carmen bought 3 books for $51.57. If each book cost $15.99 before tax was added, what tax rate did she pay? A. 1.2% B. 3.6% C. 8.5% D. 7.5% Obj. 2: 8.3B 47.97 + tax(47.97) = 51.57 Try each answer! 47.97 + 0.012(47.97) = 51.57 47.97 + 0.57564 = 51.57 47.97 + 0.036(47.97) = 51.57 47.97 + 1.72692 = 51.57 47.97 + 0.085(47.97) = 51.57 47.97 + 4.07745 = 51.57 47.97 + 0.075(47.97) = 51.57 47.97 + 3.59775 = 51.57

8. © A Very Good Teacher 2008 Discounts Discounts are always subtracted from the original price To find the discount multiply the rate by the original price Example: A pair of shoes are on sale for 30% off the regular price of $25. What is the sale price of the shoes? Obj. 2: 8.3B Original Price - Discount = Sale Price 25 - 0.30(25) = Sale Price 25 - 7.5 = $17.50

9. © A Very Good Teacher 2008 Discounts, Cont… Example: Mike saved $16 on a jacket that was on sale. If the sale price was 20% off the regular price, what was the regular price? A. $90 B. $80 C. $70 D. $32 Original Price x Rate = Discount Original Price x 0.20 = 16 Try each answer! 90 x 0.20 = 80 x 0.20 = 70 x 0.20 = 32 x 0.20 = 18 16 14 6.4 Obj. 2: 8.3B

10. © A Very Good Teacher 2008 Equations, Tables, and Graphs Equations, Tables and Graphs are different ways to represent the same data Example: Equation Table Graph Obj. 2: 8.4A y = 2x + 3 XY 0 2 3 y = 2(-1) + 3= 1 1 y = 2(0) + 3= 3 3 y = 2(2) + 3= 7 7 y = 2(3) + 3= 9 9

11. © A Very Good Teacher 2008 Equations, Tables, and Graphs, cont… Example: The table below shows a relationship between x and y. Which equation best represents this relationship? Obj. 2: 8.4A XY 04 16 28 310 A. y = 4x B. y = x + 4 C. y = 4x + 2 D. y = 2x + 4 Try the first point. 4 = 4(0) 4 = 0 + 4 4 = 4(0) + 2 4 = 2(0) + 4 Try the second point. 6 = 1 + 4 6 = 2(1) + 4

12. © A Very Good Teacher 2008 Vocabulary Rate – a comparison of numbers Speed – Distance ÷ Time Cost – amount needed to purchase an item Sales Tax – additional cost to purchase an item Discount – amount taken away from the cost of a purchase Equation – any expression with an “= sign” Table – a way to organize data Graph – a picture of data XY 0 2 3