4.3.1: Practice Problems Corequisite N.3

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The purpose of this section is for you to practice with the skills and concepts from the lesson. You will see questions directly related to the lesson. You will also see questions that apply the skills and concepts to different situations. The section will sometimes have reading material that helps explain the topics from the lesson. Later in the course, you can look back at this information as you review what you have learned.

Note that the online version of these practice problems can contain variabilized figures and values.

Question 1 highlights important quantitative reasoning skills that you will learn in this course.

Quantitative Reasoning Skill: Reading and interpreting quantitative information

The two statements shown below are about children “gunned down” in America.⁷ Read them carefully and decide what each means mathematically.

Original Statement: The number of American children killed each year by guns has doubled since 1980.

Reworded Statement (circa 2020): Every year since 1980, the number of American children gunned down has doubled.

(1) Based on the original statement and the reworded statement, which of the following comments is valid?

(i) Assume that the original statement is true. If approximately 100 children were killed by guns in 1980, the number of children killed by guns in 2020 was about 200.

(iii) Assume that the reworded statement is true. If approximately 100 children were killed by guns in 1980, the number of children killed by guns in 2020 was about 200.

This highlights the importance of reading and writing carefully about quantitative information. The original and reworded statements look very similar, but mean entirely different things:

The original statement says that the number has doubled once from 1980 to the published date (2020).
The reworded statement says that the number has doubled every year between 1980 and the published date (2020).

There are many types of investments. Putting money into a savings account or an individual retirement account are two examples of investments.

Some types of investments earn interest based on a percentage rate. People often estimate the doubling time of investments to predict how much money the investment will be worth in the future. An investment that earns 5% interest will double in value about every 14 years. Use this information to complete the missing values in the table below for $7,500 invested at 5% interest. Be sure to show your calculation work.

Complete the table by answering Questions 2-4.

Year	Value of Investment
2020	$7,500
	$15,000
	$30,000
2062

(2) In what year would the value of a $7,500 investment at 5% interest be $15,000?

(3) In what year would the value of a $7,500 investment at 5% interest be $30,000?

(4) What would the value of a $7,500 investment at 5% interest be in the year 2062?

(5) Which of the following is the best estimate for the amount of time it would take the investment in the table above to reach a hundred thousand dollars? Be sure to explain your answer.

(i) Less than 40 years

(ii) Between 40 and 60 years

(iii) Between 60 and 80 years

(iv) More than 80 years

(6) Some checking accounts pay a small amount of interest on the money in the account. In this case, interest is money that is paid to the account holder by the financial institution issuing the checking account. The interest is a percentage of the amount of money in the account. The percentage is called the annual interest rate. Compare the following two offers.

Bank of Avalon pays 0.8% with no annual fee.
Cypress Savings pays 1.5%, but charges a $10 annual fee.

Which bank would be the better offer if you have $1,000 in an account for one year?

Use the Writing Principle with your calculations to defend your answer.

(i) Bank of Avalon

(ii) Cypress Savings

Corequisite lessons are also available online. The Practice Problems section of online Corequisite lessons contains similar questions to what you see in your workbook, but the numbers and figures vary, so they are good for extra practice. Completing the Practice Problems section online will generate a score.

Tip: You can use the print version for practice. Then you can do the Practice Problems section for additional practice and a score.

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⁷ Best, J. (2001). Damned lies and statistics. University of California Press: Berkeley and Los Angeles.

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