Like many college students, Melanie applied for and got a credit card that has an annual percentage rate (APR) of 12%. The first thing she did was buy a new stereo system for $400. At the end of the month, her credit card statement said she only needed to make a minimum monthly payment of $15. Assume Melanie makes her payment when she sees her statement at the end of each month. If Melanie doesn't charge anything else and only makes the minimum monthly payments, approximately how many months would it take her to completely pay off the stereo system

31.17 months

Explanation:

For computing the number of months required to pay off the stereo system we need to apply the NPER formula i.e be shown in the attachment below:

Given that,  

Present value = $400

Future value = $0

Rate of interest = 12%  ÷ 12 months = 1%

PMT = $15

The formula is shown below:

= NPER(Rate;PMT;-PV;FV;type)

The present value come in negative

So, after applying this,  the number of months is 31.17 months

a manufacturer of printed circuit boards uses exponential smoothing with trend to forecast monthly demand of its product. at the end of december, the company wishes to forecast sales for january. the estimate of trend through november has been 200 additional boards sold per month. average sales have been around 1000 units per month. the demand for december was 1100 units. the company uses α = 0.20 and β = 0.10. make a forecast including trend for the month of january.