Rockwell hardness of pins of a certain type is known to have

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.2. (Round your answers to four decimal places.)

Solution

(a)

Mean =50

X =51

n =16

Standard Deviation SD = 1.2

z( X>=51 ) = (51-50)/(1.2/sqrt(16) )

= 3.33

Therefore,

P-value = 1 - 0.9996

= 0.0004 Answer

(b) Already correct.