## mariomintchev 2 years ago I need help with this INTEREST question

1. mariomintchev

2. mariomintchev

Here's the annuity formula: A=R*( (1+i)^n - 1 ) / (i)

3. mariomintchev

@jhonyy9 @jim_thompson5910 @karatechopper @Mertsj @TuringTest @UnkleRhaukus

4. mariomintchev

im confused about what im supposed to do

5. Best_Mathematician

not everyone have ms office

6. mariomintchev

@saifoo.khan @luis

7. satellite73

isn't this just a multiplication problem?

8. satellite73

$644.30\times 12\times 25$ is the total you pay

9. mariomintchev

i dont know ive been trying to figure it out. i did try multiplying the payments by the years but that wasnt right.

10. satellite73

you pay monthly

11. mariomintchev

ok that's right. i was multiplying bu just the years instead of years times frequency of payments

12. satellite73

ok good

13. mariomintchev

why isnt the 2nd blank 155811.6?

14. satellite73

dunno i didn't compute

15. mariomintchev

nevermind!

16. satellite73

$644.30\times 12\times 25-865.62\times 12\times 25$

17. satellite73

no that is wrong

18. mariomintchev

it wanted me to get that answer and then subtract it from the previous to get the difference

19. satellite73

$644.30\times 12\times 25-865.62\times 12\times 15$

20. mariomintchev

yup

21. mariomintchev

22. mariomintchev

can you help with this one too please?

23. satellite73

i would if i could, but i have absolutely no idea

24. satellite73

there is some formula for this that you derive by summing a geometric series, but i don't know it. maybe it is in your book?

25. mariomintchev

dont have the book. lol i have the annuity formula along with the compounding interest and simple interest formulas

26. satellite73

i guess this requires the annuity formula, because you are investing every month (or year)

27. mariomintchev

yeah thats what i used... i dont really understand the 2nd half of the question though....

28. mariomintchev

the invest up to 2,900 part

29. satellite73

use the formula for yearly at 2,900 per year

30. satellite73

i don't know it, so i can't do it

31. mariomintchev

or maybe i use the compound formula: A=P(1+ r/n)^nt