A friend tells you that her savings account doubled in 9 years. Use the Rule of 72 to estimate what the APR of her account was.

The rule of 72 says that an amount will double when the product of the percentage and the number of years equals 72...so for 8 years, you would need to earn 9%

what's that

hello from mrbilldoesmath!

answer:

the domain is the set { -2, 0, 2, 3}

discussion:

the domain is the set of x values in the ordered pairs (x,y). taking the x, or first component, of each ordered pair gives   -2, 0, 2, 3.

you,

mrb