Pre-Algebra Guided Notes Unit 7 6-5, 6-6, 6-8, 6-9, 6-10 Name

Transcription

1 Pre-Algebra Guided Notes Unit 7 6-5, 6-6, 6-8, 6-9, 6-10 Name

2 Lesson 6-5 Fractions, Decimals and Percents Percent a ratio that compares a number to Percent to Fraction Put number over 100 and simplify. Fraction to Percent Set fraction equal to n over100 OR Change fraction to decimal, then change decimal to percent. Percent to Decimal Move decimal point 2 places to the left and drop % symbol. Decimal to Percent Move decimal point 2 places to the right and add % symbol. Fraction to Decimal Divide (top divided by bottom) Decimal to Fraction Read properly and you will hear the place value which is denominator.

3 Lesson 6-6 Using the Percent Proportion is of % = 100 Set up a proportion and solve is what percent of 25? 2. What number is 8.8% of 20? is 28% of what number? is 3% of what number?

4 5. What number is 11.4% of 330? 6. What percent of 8 is 12? Set up a proportion and solve. 7. I have read 35 out of 230 pages. What percent of the book did I read? Round to nearest tenth 8. I ate 6 candy bars out of the bag of candy, which was 30%. How many candy bars were in the bag to start?

5 Lesson 6-8 Using Percent Equations is means of means Change percent to a decimal. Set up an equation and solve. 1. Find 38% of is what percent of 25? is 16% of what number? is what percent of 125? is 30% of what number? 6. 45% of 70 is what number?

6 Lesson 6-8 (2 nd day) Discounts and Total Price To find a discount: You change the percent to a decimal. Then multiply this decimal by the price of the item. This is the discount. To find the total price with a discount: 1.) You can find the discount as described above. Then subtract the discount from the price of the item. (price discount) OR 2.) If you only need the total price with the discount: Multiply the price of the item by the percent (as a decimal) you are paying. (EX: If an item is discounted 30%, then you are paying 70%) Sales Tax and Total Price To find the sales tax: You change the percent to a decimal. Then multiply this decimal by the price of the item. This is the tax. To find the total price with tax: 1.) You can find the tax as described above. Then add the tax to the price of the item. (price + tax) OR 2.) If you only need the total price with the tax: Multiply the price of the item by tax as a decimal with a one in front of it. (EX: If the tax rate is 6%, you use 1.06 If the tax rate is 4%, you use 1.04)

7 Discount the amount by which the regular price of an item is. % regular price = discount regular price discount = sale price 1. A ring costs $495. It is on sale at a 20% discount. What is the sale price of the ring? 2. A jacket costs $180. It is 35% off. What is the sale price? What if there is 6% tax? How much tax would there be on the sale price? 3. Coat is $50 and on sale for 20% off. If you buy it today, you can get an additional 10% off. What is the sale price if you buy it today?

8 Interest amount of money paid or earned for the use of money Interest = Principal Rate Time I = P R T 1. Suppose you invest $2000 at an annual interest rate of 4.5%. How long will it take for it to earn $495 in interest? 2. You place $2400 in the bank for 5 years. After 5 years, you made $552 from the interest. Find the rate.

9 Lesson 6-9 Percent of Change Tells the percent an amount has increased or decreased in relation to the original amount. % = amount of change original amount 1. Find the percent of change from 325 to In 1965, when Jon entered college, the tuition per year was $7500. In 2005 when his daughter went to the same school, the tuition was $25,500. Find the percent of change. 3. A $110 sweater is on sale for $88. What is the percent of change?

10 Lesson 6-10 Using Sampling to Predict Sample a selected smaller group chosen from a larger group Unbiased sample a large representation of a sample selected at random or without preference. Biased Sample a sample not representative of the population Identify each sample as biased or unbiased. 1. A hardware store wants feedback on its products and service. The store includes a telephone number on each receipt so customers can voluntarily call. 2. To determine the theme for the homecoming dance, the homecoming committee surveys one classroom. 3. Thirty student ID numbers are randomly selected by a computer. 4. To determine shopping habits at a department store, one male and one female shopper are randomly selected and surveyed from each of their 75 stores.

11 Use the given information to answer each question. 5. Miss Newman surveyed every tenth student in the hallway to see which sport they preferred watching: 44% preferred football, 28% basketball, 20% soccer, and 8% tennis. Out of 560 students in the entire school, how many would you expect to say they preferred watching basketball? 6. The table lists the reasons shoppers use online customer service. Reasons Percent Track Delivery 54 Product Information 24 Verify Shipping Charges 17 Transaction Help 5 Out of 350 shoppers who own a computer, how many would you expect to say they use online customer service to track packages?