
Answer:
After 11 weeks, Darnell′s savings account will have a total of $8,360.
Step-by-step explanation:
The data provided is as follows:
  n:   1     2    3     4
f (n): 260 Â 360 Â 460 Â 560 Â
Consider the data for f (n).
The series f (n) follows an arithmetic sequence with a common difference of 100 and first term as 260.
The nth term of an arithmetic sequence is:
[tex]a_{n}=\frac{n}{2}[2a+(n-1)d][/tex]
Compute the value of f (11) as follows:
[tex]f(11)=\frac{11}{2}[(2\times260)+(11-1)\times 100][/tex]
    [tex]=5.5\times[520+1000]\\\\=5.5\times 1520\\\\=8360[/tex]
Thus, after 11 weeks, Darnell′s savings account will have a total of $8,360.