standard deviation

A PERT network has 9 activities on its critical path. The standard deviation of each activity on the critical path is 3. The standard deviation of the critical path is

The standard deviation of linear dimensions P and Q are 3 µm and 4 µm, respectively. When assembled, the standard deviation (in µm) of the resulting linear dimension (P+Q) is _____...

The standard deviation of linear dimensions $$P$$ and $$Q$$ are $$3\mu m$$ and $$4\mu m$$, respectively. When assembled, the standard deviation (in $$\mu m$$) of the following line...

Consider a Poisson distribution for the tossing of a biased coin. The mean for this distribution is $$\mu $$. The standard deviation for this distribution is given by

The standard deviation of a uniformly distributed random variable $$b/w$$ $$0$$ and $$1$$ is

In a manufacturing plant, the probability of making a defective bolts is $$0.1$$. The mean and standard deviation of defective bolts in a total of $$900$$ bolts are respectively