52
A B C D
1
2
3
3
Spreadsheet
Spreadsheet programs also come equipped with builtin statistical software that allows
you to compute
P(a
≤
Z
≤
b).
For example, to compute
P(0
°
≤
°
Z
°
≤
2.43)
in Excel, enter
=NORMSDIST(2.43)NORMSDIST(0)
in any vacant cell. To compute
P(1.37
≤
Z
≤
2.43)
directly, enter
=NORMSDIST(2.43)NORMSDIST(1.37).
Web site
Follow the path
Web site
Æ
Everything for Finite Math
Æ
Chapter 8
Æ
Normal Distribution Utility
where you will find an online utility that computes areas under the normal curve to a
high accuracy.
Approximating a Binomial Distribution by a Normal Distribution
You might have noticed that the histograms of binomial distributions that we have drawn
(for example, those in Figure 1) have a very rough bell shape. In fact, in many cases it is
possible to draw a normal curve that closely approximates a given binomial distribution.
If
X
is the number of successes in a sequence of
n
independent Bernoulli trials with
probability
p
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 Spring '13
 Herbret
 Statistics, Normal Distribution, Standard Deviation, Probability theory, Binomial distribution

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