For 18% it will take 2 years to pay
For 3 years payment will be $36.50
For 14% it will take 1.9 years or 23 months
<span>A medical researcher wants to investigate the amount of time it takes for patients' headache pain to be relieved after taking a new prescription painkiller. She plans to use statistical methods to estimate the mean of the population of relief times. She believes that the population is normally distributed with a standard deviation of 18 minutes. How large a sample should she take to estimate the mean time to within 4 minutes with 97% confidence?
-----
n = [z*s/E]^2
---
n = [2.17*18/4]^2 = 96 when rounded up
</span>
