Proportions and Percents

C2L2 Proportions with Percents

Mrs. Spencer

​Algebra 1A

​C2L2 Vocabulary Notes

• ​Design: The strategy used for the collection, measurement, and analysis of data

• ​Sample: a set of items from a larger collection

• ​Simulate: To model an experiment with another experiment

• ​A percent proportion is an equation where a percent is equal to an equivalent ratio.

Multiple Choice

Complete the definition:

A _________ consists of all subjects (human or otherwise) that are being studied

• Statistics

• Number

• People

• Population

• Pueblo

Multiple Choice

Complete the definition:

A _______ is a subset of a population

• sample

• people

• population

• group

Multiple Choice

Write a proportion and solve:
Eight is what percent of 64?

• 12.5%
• 8%
• 800%
• 1/8

Multiple Choice

Write a proportion and solve:
Six is what percent of 5?

• 120%
• 83.3%
• 132%
• 64%

Multiple Choice

Write a proportion and solve:
Thirty is 20% of what number?

• 150
• 6
• 143
• 18

​Review

Percent

• Percent is the amount per hundred

• ​Percent is a number used to show the relationship of part to whole

• ​The ratio of the part to the whole can be written as an equivalent ratio with 100 in the denominator

• ​Part (is), Whole (of), Percent (%)

Set up a proportion and solve for the unknown

Multiple Choice

Allison used a 30% off coupon to purchase a sweater. If she saved $14.40, what was the original price of the sweater?

• $45.20

• $48.00

• $52.40

• $54.00

Multiple Choice

Yulia went to the clearance rack at a department store and found a shirt she wanted to buy.  The shirt was $36.00 and is on sale for $24.00.  What is the percent of the decrease?

• 33%
• 67%
• 50%
• 34%

Multiple Choice

Tickets to Disneyland are $100. The price is going to increase on January 1. What is the percent of change if the cost increases to a $120?

• 25%
• 120%

• 20%
• 50%

Multiple Choice

Juan has a coupon for 25% off her entire meal of $17.89.

What is the discount (amount he will save)?

• $13.42
• $4.47
• $4.48
• $0.44

Multiple Choice

78 is what percent of 450?

• 5%
• .17
• 17%
• 18%

More Examples​ - Take notes

​Example A - Finding an Unknown Percent

​In a capture-recapture process, 200 fish were tagged. From the recapture result, the game warden estimates that the lake contains 2500 fish.

​

What percent of the fish were tagged?

​

​Step 1: Set up a proportion

​

​Step 2: Solve for the unknown

​

​Step 3: Write the solution to the problem in words

​Example B - Finding an Unknown Total

​​In a lake with 250 tagged fish, recapture results show that 11% of the fish are tagged.

​

​About how many fish are in the lake?

​

​Step 1: Set up a proportion

​

​Step 2: Solve for the unknown

​

​Step 3: Write the solution to the problem in words

​Example C - Finding an Unknown Part

A lake is estimated to have 5000 fish after recapture experiments that showed 3% of the fish were tagged.

​

​How many fish were originally tagged?

​

​Step 1: Set up a proportion

​

​Step 2: Solve for the unknown

​

​Step 3: Write the solution to the problem in words

Multiple Choice

34% of what number is 51?

• 69
• 71
• 150
• 196

Multiple Choice

A student made an 85% on a test with 25 questions. What is the number of questions that the student answered correctly?

Round to the nearest whole number.

• 21 questions

• 22 qestions

• 23 questions

• 24 questions

Multiple Choice

There are 36 quarters in my coin collection. If my coin collection has 45% quarters, how many total coins do I have?

• 75%

• 80 %

• 75 coins

• 80 coins

Multiple Choice

Jose and his family are enjoying a vacation in Arizona. One place they really want to visit is the Grand Canyon. The total distance they will drive is 400 miles. If they have already driven 280 miles, what percent have they driven?

• 68%

• 30%

• 70%

• 43%

Multiple Choice

Leslie's class has 28 students in it. 25% of those students are home sick today. How many students are home sick?

• 4 students

• 7 students

• 11 students

• 13 students

Multiple Choice

The 9th graders at CCECHS are going to the Dodger game. 60% of the 120 students want to go to downtown LA first. How many students want to go downtown LA first?

• 72 students

• 27 students

• 54 students

• 69 students

Poll

Rate your understanding of this lesson (1 -Low to 5-High),

Action Items:  Watch more videos, redo the lesson, do more practice problems, review the notes, ask questions, take more notes, write down more examples, etc.

• 1- I need help! Pick 3 items.

• 2- I think I have it. Pick 2-3 items.

• 3-Need practice. Pick 1-2 items.

• 4-Pretty Good. Pick 1 item.

• 5-Got it. Help a classmate get it too.