# probability question utilising z scores

• Oct 31st 2012, 10:02 AM
colinb0
probability question utilising z scores
The question is:

Determine the probability of that a project will be completed in 60 weeks or less.

Context: projects usually are 60wks with a standard deviation of 10 weeks assume that times are normally distributed.

My question:

1, how is this question answered, and is it as I have set out - z= the expected outcome (60) minus the sample mean (60) divided by the standard deviation (10). is the answer 0 or z (50%)

2, what is this calculation called i.e. a discrete independent or ??

3, what should the calculation or/and equation look like.

Many thanks for you help in advance

Colin
• Oct 31st 2012, 05:27 PM
chiro
Re: probability question utilising z scores
Hey colinb0.

The calculation is called a z-score calculation. The equation looks exactly like what you have shown in 1. except in general you have a variable mean and standard deviation instead of the specific one in your question.