Which of the following list of basic NDT techniques are X ray types?

Periodically, a sample of 20 items are randomly selected from a population that is normally distributed, the average is computed, and plotted. Which of the following statements is correct?
. The average of the logarithms of the values is lognormally distributed.
. The standard deviation of the averages is equal to the standard deviation of the individuals divided by the square root of 20.
. The variance of the averages is equal to the variance of the individuals divided by the square root of 20.

A box contains 27 black and 3 red balls. A random sample of 5 balls is drawn without replacement. What is the probability that the sample contains one red ball?

The existence of a quality control manual at your key supplier means

In nonparametric statistics:
. No assumptions are made concerning the distribution from which the samples are taken.
. The parameters of the distribution do not relate to the parameters of the sample.
. The sample and the distribution must have no parameters in common.