User:Kevin Tan/Probability Distribution

Example :  If N(42, 9) , evaluate

(i) P(X < 44) (ii)P(40 < X < 45) Solution: To use the standardised normal distribution table, you’ve to understand :

1.	that 42 is the mean and 9 is the variance.

2.	Then, need to convert P(X) to P(Z)   by using the formula P(Z < $$\frac{x-\mu}{\sigma})$$

3.         4.  The area below the curve is the probability, corresponding to the value of ‘z’ and         the value from the table is just for the shaded region. 5. The graph is a symmetrical graph and we are reading the area of HALF the graph only. 6. The total area under the graph is 1 (ONE) and area of 0.5 on each side. The worked example below will hopefully make it clear,…..