In a study measuring households' familiarity with downloading pictures from the Internet, the following results were obtained $(1=$ not at all familiar, $7=$ very familiar $)$.

Level of Familiarity	Number of Households
1	22
2	26
3	34
4	40
5	32
6	28
7	18

a. Convert the number of households into percentages.

b. Calculate the cumulative percentages.

c. Construct a histogram with familiarity on the $x$-axis and frequency on the $y$-axis.

d. What are the mean, median, and mode of the distribution?