A Cutting Tool Has a Lifetime That Is Normally Distributed

Essay

A cutting tool has a lifetime that is normally distributed with an average life of 400 hours and a standard deviation of 50 hours.Present policy is preventive maintenance which requires changing all cutting tools at the end of each month.Current operations are two shifts per day and 7 working hours per shift.At 20 days per month,each cutting tool is in use 280 hours per month.(All cutting tools that fail are simply shut down until the end of the month sweep).The variable costs of replacement under the current policy are $8 per tool plus installation labor of $6 per tool.There are 40 tools in use.
-With 40 tools in use,how many are likely to fail during a month?