Amortization HELP!!! God bless you!!

[slimjim]

HERE GOES!!

A loan is being repaid with 10 installments. The principal portion of the seventh payment is $110.25 and the interest portion is $39.75. What annual effective rate of interest is being charged? My book has the answer of 8%.

WHat I have done so far is making a schedule and solve for the principal repaid which 70.50. I am stuck, CAN SOMEONE GIVE A GOOD HINT?

MY NEXT QUESTION:

A loan at j₁=9% is being repaid by monthly payments of $750 EACH. The total principal repaid in the 12 monthly installments of the 8th year is $400. What is the total interest paid in the 12 installments of the 10th year?
My book answer is $8524.76

GOD BLESS YOU IF CAN GIVE ME A HINT AS HOW TO START THIS PROBLEM.

 

[stapel]

1. A loan is being repaid with 10 installments. The principal portion of the seventh payment is $110.25 and the interest portion is $39.75. What annual effective rate of interest is being charged? My book has the answer of 8%.

WHat I have done so far is making a schedule and solve for the principal repaid which 70.50. I am stuck, CAN SOMEONE GIVE A GOOD HINT?

2. A loan at j₁=9% is being repaid by monthly payments of $750 EACH. The total principal repaid in the 12 monthly installments of the 8th year is $400. What is the total interest paid in the 12 installments of the 10th year?
My book answer is $8524.76

What formula(s) have they given you to use? Please include the definitions of the variables. Thank you!

 

[slimjim]

Amortization help

What formula(s) have they given you to use? Please include the definitions of the variables. Thank you!

S = R [(1 + i)ⁿ - 1 / i ] OR A = R [ 1-(1 + i)^-n / i]

S - accumulated value, or the amount, of an annuity
R - periodic or monthly payment of the annuity
n - number of interest conversion periods during the term of an annuity (or, in the case of a simple annuity, the total number of payments)
i - interval rate per conversion period
A - discounted value, present value, of an annuity

For the concluding payment let (X) be it.

SO, X + 110.25 [(1 + i)⁹ - 1/ i ] (1 + i ) = debt (1 + i )¹⁰

If I were to construct a table, the $110.25 would be the 7th payments as instructed for the periodic payment column and the 39.75 would be for the "Interest at (i)" column.

Let me know if you need more details.

 

[jonah2.0]

For the first part, (110.25 + 39.75)(1+i)^(-(10-7+1))=110.25
Solve for i.

For the 2nd part, 750(12)-400(1.09)^(10-8)
You can also solve for the amount of the loan and loan term as I pointed out on http://mathhelpforum.com/business-math/225324-not-so-intuive-amortization-problem.html