If A means addition (+) B means subtraction (-) C means multiplication (x) and D means (/) what is the value of expression: 6 B12 A 30 C 6 D 3 ?

The ratio of strength of solid to hollow shaft, both having outside diameter D and hollow having inside diameter D/2 in torsion is:

If a sufficient estimator exists it is a function of the _______ estimator.

If Z is a standard normal variate, the proportion of items lying between z=-0.5 and z=-3.0 is