The width W (in inches) of duralumin forged parts is normally distributed with mean: mu=0.9000 and standard deviation sigma= 0.0040. The specification limits for the part is given as 0.9000 +/- 0.0060
a) What is the probability that a part will have a width less than 0.895?
b) Given that all parts in a select group of parts are within the specification limits, what is the probability that one of these select parts has a width in the range 0.9000+/- 0.0030?