Consider the following cumulative frequency distribution:
Class ..... Cumulative Frequency
15 up to 25 .... 30
25 up to 35 .... 50
35 up to 45 .... 120
45 up to 55 .... 130

a. Construct a frequency distribution. How many observations are at least 35 but less than 45?
b. Graph a frequency histogram.
c. What percent of the observations are less than 45?