Math OER welcome page Zoom Room Zoom logo Jamboard Jamboard logo Lectures YouTube playlist Textbook textbook cover       valid HTML 4.01
Welcome Study Skills Library Playgrounds Resources Syllabus
Shapeshifting Topic Mad  Science Topic Justice Topic Health Decisions Topic Personal Finance Topic Business Decisions

Math OER
 Turn In Problems 
 Personal Finance Decisions — Saving for Retirement 

The greatest reward for a student is not a good grade. It is the willingness of his teacher to listen to him.

- Nikolay Konstantinov

homework turn in box You attempted the ten exercises for this topic. Those problems did not have an answer key. Use this form to ask me how well you did.

Before using this page, you should have your homework completed on paper. This page is only for submitting your homework. To be short and concise it lacks any diagrams, pictures, or tables needed to work the problems.

Answer every question. Then use the button at the bottom of the page to create a code by processing your answers. Copy-and-paste the code into an e-mail.


1. Tom buys a painting for $100. His friend, Eric, buys a painting for $200. Both paintings increasse in value by $30. What is the percent increase for each?

Tom 333%, Eric 666% Tom 43%, Eric 18%
Tom 233%, Eric 566% Tom 30%, Eric 15%

2. A business buys a copy machine for $2,500 by borrowing that $2,500 with a loan of 15% simple interest for three years and three months. What is the total cost (the copy machine plus the loan's interest)?

$1,218.75 $1,237.50 $3,718.75 $3,737.50

3. How much was borrowed at 120% annual simple interest for two weeks if the interest was $16.15?

$6.73 $67.30 $80.75 $349.92

4. When Huey, Dewey, and Louie entered kindergarten their uncled started a college account for them. Each account had $5,000. That one deposit grew at 9% annual interest for 13 years. For Huey the interest was compounded weekly. For Dewey the interest was compounded monthly. For Louie the interest was compounded annually. How much was each account worth at the end of the 13 years?

Huey has the most with $53.89 more than the second-place sibling
Dewey has the most with $710.76 more than the second-place sibling
Louie has the most with $382.33 more than the second-place sibling
Louie has the most with $764.66 more than the second-place sibling

5. Mr. Largo gives his 20-year-old sibling a $100 wedding present. The sibling invests it at 11% annual compound interest for 30 years. Then the sibling adds an extra $10,000, and moves the combined funds in a different investment that earns 4% annual compound interest for 10 years. What is the final value, when the sibling is 60 years old?

$2,289.23 $3,388.62 $18,191.06 $34,894.30

6. A credit card has an 18% annual interest rate. Payouts happen monthly. The loan uses compound interest. What is the annual effective interest rate?

1.5% 18% 19.5% 19.6%

7. If $3,865 is invested with 9% annual compound interest for 40 years, how much will it grow to be worth? How much less than $176,696 is your answer?

worth $37,131 less than $176,696
worth $55,299 less than $176,696
worth $65,825 less than $176,696
worth $162,782 less than $176,696

8. Fiddle around using the sum of annuity due formula to find what annual deposit (principal) would grow to $176,696 over 40 years at 9% annual interest. (Hint: an annual deposit of $400 is too small, but $550 is too big.)

$453.24 $479.77 $506.30 $5,876.35

9. How does the long-term financial cost of infant care compare to saving for kids' college expenses? The "big three" child care centers in Eugene cost roughly $13,000 per year. Use the sum of annuity due formula for two years (when the infant is age 1 and 2), and then the compound interest formula for sixteen years (until the child is 18). If the family instead saved the infant care money and earned a 5% annual interest rate, how much would be saved towards the child's college tuition?

$27,982.50 $28,377.37 $56,754.74 $61,082.29

10. In a certain computer game the archer queen gets 10% stronger every time she gains a level. Two brothers play the game. The younger brother has a level 20 archer queen. The older brother has a level 27 archer queen. Roughly how much stronger is the older brother's archer queen?

50% stronger 135% stronger
74% stronger 200% stronger