25. The number of miles per gallon for a 2009 Corvette has a normal distribution with
mean 15 mpg and standard deviation 0.5 mpg. What is the probability that a
randomly chosen corvette gets exactly 15 miles per gallon?
ANS____P(X=15) = 0
__
26. Suppose 30% of OSU students are in favor of having casinos in Ohio.
Two OSU
students are selected at random; let X equal the number of students in the sample
who are in favor of casinos in Ohio. Write down the
probability distribution
for
X. (Remember we discussed in lecture what a probability distribution is.)
Binomial: n=2 p=0.3
k
0
1
2
P(X=k)
0.49
0.42
0.09
27. Suppose 85% of your employees got raises last year. You sample 100 employees
at random and count the number who got a raise. What is the chance that at least
80 of the employees got a raise?
Normal Approximation to the Binomial
10
85
85
.
0
100
=
×
=
np
10
15
15
.
0
100
)
1
(
=
×
=

p
n
85
85
.
0
100
=
×
=
=
np
X
μ
571
.
3
75
.
12
15
.
0
85
.
0
100
)
1
(
=
=
×
×
=

=
p
np
X
σ
40
.
1
571
.
3
85
80

=

=

=
X
Z
P(X > 80) = P(Z > 1.40) = 1  0.0808 = 0.9192
ANS__0.9192_____
4
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View Full Document28. Suppose a manufacturer has recorded its cost of electricity (in dollars) and the
total number of hours of machine time for their factory during a certain number of
weeks. Using this information, how much does the cost increase for each
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 Winter '12
 Johnson
 Statistics, Normal Distribution, Standard Deviation

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