Question

Question #de9db

Answer 1

Total interst is `6840` dollars.

Explanation:

To begin with, let's see how much the company will pay in the first two months.

[First month]
Interest: `$36000 * 0.02 = $720`
Principal: `$2000`
Total: `$2720`

[Second month]
Interest: `$34000 * 0.02 = $680`
Principal: `$2000`
Total: `$2680`

How about the last month?
[Last(18th) month]
Interest: `$2000 * 0.02 = $40`
Principal: `$2000`
Total: `$2040`

Then, what is the sum of the interest?
`720,680,...,40` is an arithmetic progression.
The sum of an arithmetic progression is
`S=1/2 n(a_1+a_n)` ,where
`n`: number of terms
`a_1`: first term
`a_n`: last term.

Substitute `n=18, a_1=720, a_n=40` to this formula.
`S=1/2 *18*(720+40)=6840`

Thus, the total interst the company has to pay is `$6840`.