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1.
Suppose
z
is a standard normal variable and using Table A1:
What is the relative frequency of observations from
z
greater than
.58
?
P(Z > 0.58) = 1 – P(Z < 0.58) = 1 – 0.2810 = 0.7190
What is the relative frequency of observations from
z
between
1.0
and
1.0
?
P(1.0 < Z < 1.0) = P(Z < 1.0)  P(Z < 1.0) = 0.8413 – 0.1587 = 0.6826
What is the eightieth percentile of
z
? [That is, find the value such that approximately 80% of the
standard normal observations fall below
z
.]
Z = 0.84 from the table find the 4digit probability closest to
0.8000
What is the first quartile, Q1, of
z
?
[That is, find Q1 such that the relative frequency of observations
from
z
falling below Q1 is approximately .2500]
Z = – 0.67
from the table find the 4digit probability
closest to 0.2500
2.
The Chapin Social Insight Test evaluates how accurately the subject appraises other people.
In the
reference population used to develop the test, scores were approximately normally distributed with mean
25 and standard deviation 5.
The range of possible scores is 0 to 41.
What proportion of the population has scores below 20 on the Chapin test?
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 Spring '08
 BARROSO,JOAOR
 Statistics

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