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Warm Up 1. 14,000 is 2 % of what number? 2. 39 is 13% of what number?

1. 2. 1. 2. Warm Up 1. 14,000 is 2 % of what number? 2. 39 is 13% of what number? 3. 37 % of what number is 12? 4. 150% of what number is 189?. 560,000. 300. 32. 126. Lesson 2. Percent Increase and Decrease. amount of change original amount. percent of change =.

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Warm Up 1. 14,000 is 2 % of what number? 2. 39 is 13% of what number?

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  1. 1 2 1 2 Warm Up 1. 14,000 is 2 % of what number? 2. 39 is 13% of what number? 3. 37 % of what number is 12? 4. 150% of what number is 189? 560,000 300 32 126

  2. Lesson 2 Percent Increase and Decrease

  3. amount of change original amount percent of change = Percents can be used to describe a change. Percent of change is the ratio of the amount of change to the original amount. Percent of increase describes how much the original amount increases. Percent of decrease describes how much the original amount decreases.

  4. amount of decrease 4 16 original amount 4 16 Class Example Find the percent of increase or decrease from 16 to 12. This is a percent of decrease. 16 – 12 = 4 First find the amount of change. Set up the ratio. Find the decimal form. Write as a percent. = 0.25 = 25% From 16 to 12 is a 25% decrease.

  5. amount of increase 9 original amount 45 9 45 Partner Practice Find the percent increase or decrease from 45 to 54. This is a percent of increase. 54 – 45 = 9 First find the amount of change. Set up the ratio. = 0.20 = 20% Find the decimal form. Write as a percent. From 45 to 54 is a 20% increase.

  6. amount of increase 15 original amount 50 15 50 Individual Practice Find the percent increase or decrease from 50 to 65. This is a percent of increase. 65 – 50 = 15 First find the amount of change. Set up the ratio. = 0.30 = 30% Find the decimal form. Write as a percent. From 50 to 65 is a 30% increase.

  7. 26 amount of increase 72 original amount 26 72 Class Example When Jim was exercising, his heart rate went from 72 beats per minute to 98 beats per minute. What was the percent increase to the nearest tenth of a percent? 98 – 72 = 26 First find the amount of change. Set up the ratio.  0.361  36.1% Find the decimal form. Write as a percent. From 72 to 98 increases by about 36.1%.

  8. amount of decrease 0.40 1.25 original amount 0.40 1.25 Individual Practice In 2005, a certain stock was worth $1.25 a share. In 2006, the same stock was worth $0.85 a share. What was the percent decrease? 1.25 – 0.85 = 0.40 First find the amount of change. Set up the ratio. Find the decimal form.Write as a percent. = 0.32 = 32% The value of the stock decreased by 32%.

  9. Discount is the difference between the regular price and the sale price of an item.You can use percent of decrease to find discounts. Markupis the difference between the wholesale cost and the retail price of an item.You can use percent of increase to find markups.

  10. Practice Sarah bought a DVD player originally priced at $450 that was on sale for 20% off. What was the discounted price? Method 1: Multiply, then subtract. (450)(0.20) = 90 Find 20% of $450. This is the amount of discount. 450 –90 = 360 Subtract $90 from $450. Method 2: Subtract, then multiply. 100% – 20% = 80% Find the percent Sarah pays. (450)(0.80) = 360 Find 80% of 450. The discounted price was $360.

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