字幕列表 影片播放 列印英文字幕 You want to buy a $222,000 home. You plan to pay 10% as a down payment and take out a 30-year loan for the rest. Part a, how much is the loan amount going to be? Because you are putting 10% down, the loan amount is going to be 90% of $222,000 since 100% minus 10% is 90%. So for part a we have to find 90% of 222,000. To find the percent of a number, we convert the percent to a decimal and multiply. 90% as a decimal is 0.90, or just 0.9, giving us 0.9 times 222,000. And now going to the calculator 0.9 times 222,000 is 199,800 and therefore the loan amount is $199,800. And then for part b, what will your monthly payments be if the interest is 6%? To answer this question we will use the TI-84 TVM solver. Let's begin by determining the required information below where capital N is the total number of payment periods. Because you are paying monthly for a period of 30 years, capital N is 30 times 12, which is 360. There are 360 months in 30 years. I% for part b is 6% and therefore we enter six here. PV stands of present value, which is a beginning loan amount, which we now know is 199,800. This is positive because you are receiving that amount of money. PMT stands for payment amount, which we are solving for. FV stands for future value, which is zero because after 30 years the loan is paid off and the balance is zero. And payments per year and compounds per year will both be 12 because you are paying monthly and we assume the interest is compounded monthly. And we always leave the PMT option at the bottom set on end. And now we go to the calculator and then we press apps, enter, enter, then enter the information. Capital N is 360, enter. I% is six, enter. PV is 199,800, this is the present value, enter. We are solving for the payment, so we'll come back to this row, enter. Future value is zero, enter. And payments per year and compounds per year are both 12. And notice how we do have PMT set on end. To solve for the monthly payment we go up to the row for PMT or payment and press alpha, enter. Notice how it's negative because this is the amount you have to pay each month which means the monthly payment when the interest rate is 6% is $1,197.90 to the nearest cent. So using the solver, even though the PMT amount is negative, we do enter a positive value for part b for the monthly payments. And then for part c, what will your monthly payments be if the interest rate is 7%? To answer this question using the TVM solver we simply change the 6% to 7% and then solve for PMT again. So going back to the calculator, again we change the six to a seven for the interest rate. Everything else stays the same. And now we go down and solve for the payment again. So go down to the payment row, the cursor does have to be in this row to solve for this, and then we press alpha, enter. So if the interest rate changes to 7% then the monthly payments are going to be $1,329.27. Looking at the monthly payments, notice how when the interest rate goes up from 6% to 7% the monthly payment goes up by over $130 which is why the interest rate of a mortgage is so important. I hope you found this helpful.