Rule of 72

Your returns (or interest rate) are 8% a year. How long before your investment doubles?

• 9 years
• 8 years
• 7 years
• Never

Tags

CCSS.7.RP.A.3

Your returns (or interest rate) are 9% a year. How long before your investment doubles?

• 9 years
• 8 years
• 7 years
• They won't

Tags

CCSS.7.RP.A.3

Your returns (or interest rate) are 6% a year. How long before your investment doubles?

• 18 years
• 16 years
• 12 years
• 8 years

Tags

CCSS.HSF.LE.A.4

Your returns (or interest rate) are 1% a year because they are in a savings account. How long before your savings doubles?

• 72 years
• 36 years
• 1 year
• They will never double

Tags

CCSS.HSF.LE.A.4

BONUS! Inflation is 3% a year. You pay 2% in fees a year. Your returns (or interest rate) are 8% a year. How long before your investment doubles?

• 9 years
• 8 years
• 24 years
• 72 years

Both Madison and Jeremiah invested $2,500 in an

account. Madison’s interest rate is 5.75% and is

compounded annually. Jeremiah’s account earns

a simple interest rate is 5.75%. Neither will make

any additional deposits or withdrawals. What is

the difference in the interest earnings between

Madison and Jeremiah’s accounts at the end of 6

years?

Mathematical Equivalence

ON