Respuesta :
Answer:
an = 225 (1.04) ^ (n-1)
Step-by-step explanation:
We start with the initial amount
a1 = 225
Then we know the amount in the account the 6th month
a6 = 273.75
The formula is
an = a1 r^(n-1)
273.75 = 225 (r) ^ 5
Divide each side by 225
273.75/225 = 225/225 (r) ^ 5
1.216666666 = r^5
Take the 5th root of each side
1.216666666 ^ 1/5 = r^5 ^ 1/5
1.04 = r
The formula becomes
an = 225 (1.04) ^ (n-1)
Answer:
D. [tex]a_n=225*(1.04)^{n-1}[/tex]
Step-by-step explanation:
Let's use the geometric sequence recursive formula: [tex]a_n=a_1r^{n-1}[/tex], where [tex]a_n[/tex] is the nth term, [tex]a_1[/tex] is the first term, and r is the common ratio.
We see that since in the first month, Monique had $225 already, then that means [tex]a_1=225[/tex]. We just need to find the common ratio. Let's use the information given about how much money she has in the sixth month. This means that [tex]a_6=273.75[/tex]. Plug this into the formula to find r:
[tex]a_n=a_1r^{n-1}[/tex]
[tex]a_6=a_1r^{6-1}[/tex]
[tex]273.75=225*r^5[/tex]
[tex]r^5=1.217[/tex]
r ≈ 1.04
Thus, our formula is: [tex]a_n=225*(1.04)^{n-1}[/tex], which is choice D.