Using the normal distribution, find the probability that a population with a
mean of 35 and a standard deviation of 8 will produce a sample mean of less 34
in a sample of size 64.
Find the test statistic
Draw a normal curve. Draw a green line at -1. We want to find the
area to the left of the green line.
If you have the same kind of normal table as you find on this site
http://www.stat.ucla.edu/~ywu/teaching/normal.pdf
It gives the area from the far left to the z-score. So you will just go down
the leftmost column to -1.0 and since there are no more decimals, go to the
first column beside that and you see 0.1587.
That's the desired probability, 0.1587
However, if you have the kind of normal table on this site
http://www.mathsisfun.com/data/standard-normal-distribution-table.html
This kind of table gives the area from the center line to the z-score. So you
go down the leftmost column to 1.0 and since there are no more decimals, go to
the first column beside that and you see 0.3413.
However since that is the area between the center line and the z-score, you
must subtract that value from 0.5
0.5000
-0.3413
-------
0.1587
Edwin