Consider the following cumulative relative frequency distribution.
Class .......... Cumulative Relative Frequency
150 up to 200 ...... 0.10
200 up to 250 ...... 0.35
250 up to 300 ...... 0.70
300 up to 350 ...... 1

a. Construct a relative frequency distribution. What percent of the observations are at least 250 but less than 300?
b. Graph an ogive.