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IM: 7.4.8: Percent Increase and Decrease with Equations (Lesson)

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Last updated 11 months ago
14 questions
8.1: Number Talk: From 100 to 106
8.2: Interest and Depreciation
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8.3: Matching Equations
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8.4: Representing Percent Increase and Decrease: Equations
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How do you get from one number to the next using multiplication or division?
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Question 1
1.

From 100 to 106

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Question 2
2.

From 100 to 90

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Question 3
3.

From 90 to 100

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Question 4
4.

From 106 to 100

Question 5
5.

Money in a particular savings account increases by about 6% after a year. How much money will be in the account after one year if the initial amount is $100? $50? $200? $125? x dollars? If you get stuck, consider using diagrams or a table to organize your work.

Question 6
6.

The value of a new car decreases by about 15% in the first year. How much will a car be worth after one year if its initial value was $1,000? $5,000? $5,020? x dollars? If you get stuck, consider using diagrams or a table to organize your work.


Question 7
7.

Which equation matches this situation?

The water level in a reservoir is now 52 meters. If this was a 23% increase, what was the initial depth?

Question 8
8.

Which equation matches this situation?

The snow is now 52 inches deep. If this was a 77% decrease, what was the initial depth?

An astronaut was exploring the moon of a distant planet, and found some glowing goo at the bottom of a very deep crater. She brought a 10-gram sample of the goo to her laboratory. She found that when the goo was exposed to light, the total amount of goo increased by 100% every hour.
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Question 9
9.

ow much goo will she have after 1 hour? After 2 hours? After 3 hours? After n hours?

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Question 10
10.

When she put the goo in the dark, it shrank by 75% every hour. How many hours will it take for the goo that was exposed to light for n hours to return to the original size?

Question 11
11.

The gas tank in dad’s car holds 12 gallons. The gas tank in mom’s truck holds 50% more than that. How much gas does the truck’s tank hold? Explain why this situation can be represented by the equation (1.5)\cdot12=t. Make sure that you explain what t represents.

Write an equation to represent each of the following situations.
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Question 12
12.

A movie theater decreased the size of its popcorn bags by 20%. If the old bags held 15 cups of popcorn, how much do the new bags hold?

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Question 13
13.

After a 25% discount, the price of a T-shirt was $12. What was the price before the discount?

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Question 14
14.

Compared to last year, the population of Boom Town has increased by 25%.The population is now 6,600. What was the population last year?