The Heavy Duty Co. utilizes a machine for a new production process, which motor occasionally breaks down and requires a major overhaul because of its heavy-duty use. If that is the case, the old motor needs to be replaced by a new one. The manufacturer has provided the company with information about the durability of the motors (number of days of usage until a breakdown occurs), shown in the following table.

\fDay Prob. of breakdown 1, 2, 3 4 0.25 0.5 O 0.25 7 or more 0