Question

Find the sum of a finite geometric series. Jimmy’s dad gave him $100 on his birthday, which is January 1. Jimmy deposited the $100 in his savings account the same day. At the beginning of every month thereafter, Jimmy decides to deposit three times the amount he did in the previous month. On June 15 of the same year, the amount in Jimmy’s account will be $. NextReset

Answer 1

72900, because 100*3^6= 72900

Answer 2

$36400.

Explanation:

We are given that a finite geometric series

We have to calculate sum of finite geometric series

First term = $100

Second term= 3 times the amount in previous month=$300

Third term =$900

Total months =6

n=6

Common ratio ,r=
`(300)/(100)=3`

Using formula

`S_n=(a(r^n-1))/(r-1)` when r> 1

`S_6=(100(3^6-1))/(3-1)`

`S_6=(100*728)/(2)=$36400`

Hence, the amount in Jimmy's account will be $36400.