Fundamental Stats - Normal Distribution - Unstandardising - Summary

STA1003: Fundamental Statistics


Normal Distribution – Unstandardising
Overview:
 Recognising an ‘unstandardising’ context;
 Using the Standard Normal Table as applied to an ‘unstandardising’
context;
 Using the z-score in the ‘unstandardising’ formula in context.

Using the Standard Normal Table ‘backwards’:
 also use the Standard Normal Table ‘backwards’
 Suppose we know an area or proportion. . .
 . . . then we can find the corresponding z-score. . .
 . . . and hence the observation
 We use the unstandardising formula


 Use a diagram when problem-solving with a Normal model!

Follow these steps to unstandardise. .
1. Draw a diagram!
2. Use the Standard Normal Table to find the z-score
3. Use this z-score in the unstandardising formula
4. Work out the answer