Chapter 12 Solutions
12.4
a. A population proportion is the proportion (percentage) of the entire population that has the
specified attribute.
b. p
c. A sample proportion is the proportion (percentatge) of a sample from the population that has
the specified attribute.
d.
̂
e. The “number of successes” is an abbreviation for the number of members of the sample that
have the specified attribute, and it is denoted by the letter x.
f. The “number of failures” is an abbreviation for the number of
members of the sample that do
not have the specified attribute, and it is denoted by n =
x, where n is the size of the sample
g.
̂
= x/n
12. 5
a. p = 2/5 = 0.4
b.
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c. The population proportion is marked by the vertical line below.
d.
̂
∑
̂
⁄
⁄
e. The answer to part a and part d are the same.
̂
is a sample mean. The mean of the sampling
distribution of
̂
is the same as the mean of the population, which is p.
12.23
̂
⁄
; The 95% confidence interval is
̂
⁄
√
̂( ̂)
√
(
)
(
)
12.26
n = 1,516, x = 985, and n = x = 531. Both x and n = x are at least 5.
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 Spring '14
 Statistics

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