One effect of the great recession was to lower the interest rate on fixed-rate mortgages. A sample of 30-year fixed-rate mortgage rates taken from financial institutions in the Pacific Northwest resulted in the following:

3.79 4.03 3.92 3.87 3.86 3.93 3.87 3.69 3.99 3.88 3.91 3.81 3.85 3.81 3.65 4.15 3.98 3.82 4.08 3.84 3.95 4.03 3.96 3.69 3.97 4.08 3.86 3.82 3.83 4.19 3.49 3.49 3.75 3.46 3.92 3.67 3.63 3.81 3.86 4.15 3.85 4.01 3.93 4.02 4.09

a. Using Excel, construct a histogram with eight classes.

b. Determine the proportion of 30-year fixed mortgage rates that are at least 3.76%.

c. Produce an ogive for the data.