a) The mean life of washing machines comes to the market is 1000 days, with a standard deviation of 50 days. Assume the life of the washing machines follows a normal distribution. If 1000 washing machines are shipped, use the unit normal distribution area table to find that how many would need replacement before 365 days?

b) A carpenter is designing the interior doors in a residential building. He wants to make high enough so that 50+ percent of the people using the doors will have at least a one foot clearance. Assuming that the heights will be normally distributed, with a mean of 60+ inches and a standard deviation of 3 inches, use the unit normal distribution area table to find how high the engineer must make the doors.

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