A Certain article that studied the life distribution of microdrills reported the following observations, listed in increasing order on drill lifetime (number of holes that a drill machines before it breaks) when holes were drilled in a certain brass alloy. 11 59 81 105 161 14
61 84 105 168 20 65
85 112 184 23 67 89
118 206 31 68 91 123
248 36 71 93 136 263

Required:
a. Why can a frequency distribution not be based on the class intervals 0â50, 50â100, 100â150, and so on?
b. Construct a frequency distribution and histogram of the data using class boundaries 0, 50, 100, . . . , and then comment on interesting characteristics.
c. Construct a frequency distribution and histogram of the natural logarithms of the lifetime observations, and comment on interesting characteristics.
d. What proportion of the lifetime observations in this sample are less than 100? What proportion of the observations are at least 200?