Answer:
Step-by-step explanation:
The common ratio is given as 2, so the base of any exponential must be 2 (not -2 or 2.25). The 4th term is negative, so the initial value must be negative (since the multiplying factor is positive). The only selection matching these requirements is d.
You know the general term is ...
... an = a1·r^(n-1)
so the 4th term is
... -18 = a1·2^(4-1) = 8·a1
Then the first term is ...
... a1 = -18/8 = -2.25 . . . . . confirms our choice of answer d.
Answer:
Step-by-step explanation:
Any time you have compounding more than once a year (which is annually), unless we are talking about compounding continuously, you will use the formula
Here's what we have:
The amount after a certain time that she has in the bank is 4672.12; that's A(t).
The interest rate in decimal form is .18; that's r.
The number of times the interest compounds is 12; that's n
and the time that the money is invested is 3.5 years; that's t.
Filling all that into the formula:
Simplifying it down a bit:
Raise 1.015 to the 42nd power to get
4672.12 = P(1.868847115) and divide to get P alone:
P = 2500.00
She invested $2500.00 initially.