Your answer is correct. Look at it this way............ the interest rate per month is .0116666
Let S= Sum at the end of the interest period, So = the amount of money at the beginning of the period.
In our problem, S = 2So, So the formula on a monthly basis is S = So(1+.011666)m (m = # of months)
2So=So(1.011666)m then 2 = (1.011666)m, or ln(2) = (m)ln(1.011666)
m = ln(2)/ln(1.011666) = 59.759 months = 4.98 years
Mark J.
tutor
Jac, since I don’t have or use a 30XA calculator, I cannot mimic your calculation to troubleshoot the oddity! Sorry.
Report
05/25/19
Rachel C.
Hi Jac, I believe you may be missing a set of parenthesis in your calculator input. In your calculator are you putting in ln(2)/(12*ln(1+0.14/12)) with a set of parenthesis surrounding the entire denominator? If you put ln(2)/12*ln(1+0.14/12), your calculator follows orders of operation. It first computes ln(2)/12 and then multiplies that quantity by ln(1+0.14/12). Let me know if this answers your question. If not, we can always go back to the drawing board to figure it out! Rachel
Report
05/25/19
Jac V.
Why is it that when I plug in my numbers along with "ln" in my 30XA calculator, I am not getting the correct answer? The numbers I input in the formula are correct, but once I plug all that into the calculator, I don't get the right answer. The "ln" throws me off. Can you help?05/25/19