z distribution

1. Understanding the Z Scores

2. Note
• A standard normal curve is a
normal probability distribution
that has a mean = 0 and
standard deviation = 1.
0 1
1

3. The Areas Under Normal Curve

4. Find the Area under the curve z=0 and z=1 by
looking at the curve
the Area under the curve z=0 and z=1 is
= 0.6827/2
= 0.34135

5. Find the Area under the curve z = -2 and z =0
The Area under the curve z=-2 and z=0 is 0.47725

6. Find the Area under the curve z < -2
= (1 - 0.9545)
2
= 0.02275

7. Find the Area under the curve z > -2
= 1 - (1 - 0.9545)
2
= 0.97725

8. Find the Area under the curve z -1 and z = 2
= 0.9545 - 0.6827
2 2
= 0.1359
therefore ;
= 0.9545 - 0.1359
= 0.8186

9. Find the Area under the curve z =0 and z = 1.45
we can now introduce Z table

11. In the Z table, the 1/2 of the curve were
measured

12. Find the Area under
the curve z=0 and z=1
by looking at
theTABLE
= 0.3413

13. Find the Area under the curve z < -2
= 1 - ( 0.4772 + 0.5)
= 0.0228