The reliability of two types of machines used in the same manufacturing process is to be tested. The first machine failed to operate correctly in 45 out of 300 trials while the second type failed to operate correctly in 50 out of 250 trials. Calculate the standard deviation of the sampling distribution for the difference between the sample proportions.

Select one:

A.

0.0012

B.

0.0326

C.

0.1727

D.

0.134