I'm not sure why your subject line refers to "the number
e"...?
Just plug into the compound-interest formula:
. . . . .A=P(1+nr)nt
...where
A is the "ending amount",
P is the "beginning amount",
r is the "interest rate" (expressed as a decimal),
n is the "number of compoundings" (usually "per year"), and
t is the "number of years".
For instance, "monthly" means n = 12; "yearly interest rate of 16%" means r = 0.16; "invested for nine months" means t = 9/12 = 0.75.
If the investment "P" is compounded quarterly at an interest rate of 8%, then what are the values of "r" and "n"? (I would guess that you're supposed to
assume that t = 1, but the exercise should have stated this.) Plug these values in, and simplify the stuff after the "P" in the formula. This will give you your answer.
If your book wants you to do this some other way, please reply with clarification. Thank you.
Eliz.