Question

Calculate S(17) for the geometric series 256 - 128 + 64 - 32 + ... using the finite geometric sum formula. Round your answer to three decimal places.

170.668
0.004
511.996
168,151.254

Find a(5) for the geometric sequence in which S(6) = 63 and the common ratio r = 2.

-16
1
31
16

In 2010, Rooney got his first job and paid $7,004.18 in federal income tax. For the next 6 years, his income taxes increase by 1.5% each year. When Rooney finishes paying his taxes for 2016, how much will he have paid in income taxes since he first got the job in 2010?

$225,337.60
$43,632.90
$51,291.57
$7,658.67

I've been trying to solve these for a while but now my brain's fried. I feel like the solutions are on the tip of my tongue because I've tried working all of these out and I seem really close but I still manage to get them wrong:/ Please help?

Answer 1

Answer 1st question: .004 because the sequence is going down and .004 is the only # going below 32.
Answer 2nd question:so the common ration is 2 which means that you have been multiplying by 2 to get 63. You are at A(6) and want A(5), so instead of multiplying divide by 2. You should get 31.5 or 31.
Answer 3rd question: I'm not sure about but it might be 51,291.57

Answer 2

Answer 3 was correct, but the 1st and 2nd one were not. I think the first one might have been c and the 2nd one was d, 16.

Answer 3

1. 170.668
2. -6.250
3. 16
4 51,291.57

Answer 4

1. .004
2. 16
3. 51,291