Originally Posted by

**Johnboe** Q: To avoid a complete shutdown of the assembly line if a component fails, major manufacturing companies operate on the principle of preventative maintenance. the lifetime of one component is normally distributed with a mean of 325h and a standard deviation of 20h. How frequently should the component be replaced so that the probability of its failing during operation is less than 0.01?

A: I don't exactly understand it.

What exactly do I do? I tried stuff like P(x<0.01) etc but that doesnt work.

Is it something to do with making it =0.01?