The viscosity of an industrial paint, as tested by the Ford Cup method, is specified to be 34 secs ± 1 sec. Fifteen batches of the paint have been tested, and the results are shown below:

33.75  33.05  34.00  33.81  33.46  34.02  33.58  33.27

33.49  33.20  34.62  33.00  33.54  34.12  33.84

(a) From the sample, does it seem that the population mean is on target?

(b) Find the 95% confidence interval for the population mean.

(c) Using some SIMPLE test or tests, check to see if the data is "reasonably" Normal.

(d) What percentage of batches is likely to be outside the specification in the long run?