Question

I really need help with this question. Can anyone please help me? I have been stuck on this problem for days now.

The number of visitors to a website in the first week is 50. The number of visitors each week is double the number of visitors the previous week. What is the total number of visitors to the website in the first 8 wk? Show your work.

Answer 1

yay, geometric sum
an=8(2)^(r-1)
anyway, sum of geometric sequence where a1=first term and n=which one and r=common ratio is

`S_n=(a_1(1-r^n))/(1-r)`
so
first term is 50
common ratio is 2
n=8


`S_8=(50(1-2^8))/(1-2)`

`S_8=(50(1-256))/(-1)`

`S_8=-50(-255)`
S8=12760 visitors in first 8 weeks