A random sample of 20 tins of oil gave an average weight of 4.95 Kgs with a SD of 21 Kg . Do you accept the ?

Question

A random sample of 20 tins of oil gave an average weight of 4.95 Kg with a SD of 21 Kg . Do you accept the hypothesis of weight of 5 Kg per tin at 1% level (The value of Z at 1% level is 2.58)

Answer 1

No.  sd 21 and mean is 4.95 ?!?!  so you've invented anti-gravity?

The very large sd indicates that the population can't possibly be gaussian.  The huge sd (relative to the mean) indicates that you need to sample a whole lot more to get a answer you can be confident with.

Forget about Z, and look at the bigger picture.