Simple Interest: Loan payments of $700 due 3 months ago and $1000 due today...

[chabongden]

I have a question for my math practice but i did several ways but i still got the wrong answer, please help:
Loan payments of $700 due 3 months ago and $1000 due today are to be paid by a payment of $800 in two months and a final payment in five months. If 9% interest is allowed, and the focal date is five months from now, what is the amount of the final payment.
I calculated by using future value formula: S=P(1+r*t) because every payments will happen before the focal day.
The first method i tried was:
700(1+.0.09*8/12) + 1000(1+0.09*5/12) + 800(1+0.09*3/12)= 2597.5 (wrong answer)
2nd attemp:
700(1+0.09*8/12) + 1000(1+0.09*5/12)= 800(1+0.09*3/12) + X( the focal day)
==>X= 961.5 (also wrong)
I don't really see what i did wrong here because i have done several excercises which have similar format. Can anyone help me?:smile:

P/s: I don't really know what the answer is because the practice system just tell me whether my answer is true or false.

 

[chabongden]

In fact, i don't really know the answer, because my teacher is using a system like when you put your answer there, it will tell you whether it is true or false( not the answer. I really got confused with this question.

 

[JeffM]

I have a question for my math practice but i did several ways but i still got the wrong answer, please help:
Loan payments of $700 due 3 months ago and $1000 due today are to be paid by a payment of $800 in two months and a final payment in five months. If 9% interest is allowed, and the focal date is five months from now, what is the amount of the final payment.
I calculated by using future value formula: S=P(1+r*t) because every payments will happen before the focal day.
The first method i tried was:
700(1+.0.09*8/12) + 1000(1+0.09*5/12) + 800(1+0.09*3/12)= 2597.5 (wrong answer)
2nd attemp:
700(1+0.09*8/12) + 1000(1+0.09*5/12)= 800(1+0.09*3/12) + X( the focal day)
==>X= 961.5 (also wrong)
I don't really see what i did wrong here because i have done several excercises which have similar format. Can anyone help me?:smile:

P/s: I don't really know what the answer is because the practice system just tell me whether my answer is true or false.

You really cannot tell from the information given. Is interest to be accrued on the 700 from 3 months ago? is it simple interest, or is it being compounded monthly? I get you may be giving what the problem provided, but in actual practice those kinds of detail would need to be specified or else you will end up talking to lawyers.