What requirements are necessary for a normal probability distribution to be a standard normal probability​ distribution?

represent the mean and,

represent the deviation

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".  

Solution to the problem

Let X a random variable distributed normally. For this case we just need to conditions in order to satisfy a standard normal distribution

represent the mean and,

represent the deviation

On this case we say that is a normal standard distribution.

4/6 = 2/3

so it should take 3/3 hours per man. so 9 hours is the answer 3*3 =9

step-by-step explanation:

its the second choice.

step-by-step explanation:

the elements in the range will be 7 less than the elements in the domain.