A recent trend in the auto financing market is an increase in the length of new car loans. According to Experian, 11% of new car loans in 2009 were between 73 and 84 months in length. Suppose a random sample of 260 new cars loans in 2014 was selected and found to have 47 that were between 73 and 84 months in length.

a. Construct a 90% confidence interval to estimate the actual proportion of new car loans that are between 73 and 84 months in length in 2014.

b. What is the margin of error for this sample?

c. Is there evidence that this proportion has changed since 2009 based on this sample?