OM – 210, Summer A2010, (Prof.
Sid Das)
HOMEWORK – 2, (68 points)
Please answer on a SCANTRON sheet.
WRITE YOUR NAME AND CLASS TIME ON THE TOP OF YOUR SCANTRON
SHEET.
HOMEWORK DUE DATE is
June 16, 2010.

Problem A
The manager of a grocery store claims that the average time that customers spend in checkout
lines is 20 minutes or less.
A sample of 36 customers is taken.
The average time spent on
checkout lines for the sample is 24.6 minutes; and the sample standard deviation is 12 minutes.
Conduct a hypothesis test (at 0.05 level of significance) to determine if the mean waiting time for
the customer population is significantly more than 20 minutes.
ANSWER QUESTIONS 1  4.
1. The correct hypotheses for the test are:
a.
H
0
is:
μ
≥
20;
H
a
is:
μ
<
20
b.
H
0
is:
μ
≤
20;
H
a
is:
μ
>
20
c.
H
0
is:
μ
>
20;
H
a
is:
μ
≤
20
d.
H
0
is:
μ
<
20;
H
a
is:
μ
≥
20
2. The observed value of the test statistic is:
3.
The pvalue is:
4.
The null hypothesis should:
Problem B
A random sample of 16 students selected from the student body of a large university had an
average age of 25 years with a standard deviation of 2 years. Conduct a hypothesis test (at 0.05
level of significance) to determine if the average age of the population of students at the
university is significantly different from 24 years.
Assume that the distribution of the population
of ages is normal.
BASED ON THIS PROBLEM  ANSWER QUESTIONS 5 THROUGH 7 BELOW.
5. The correct hypotheses for the test are:
a.
H
0
is:
μ
≥
24;
H
a
is:
μ
<
24
b.
H
0
is:
μ
≤
24;
H
a
is:
μ
>
24
c.
H
0
is:
μ
is not equal to 24;
H
a
is:
μ
=
24
d.
H
0
is:
μ
=
24;
H
a
is:
μ
is not equal to 24.
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6. The observed value of
the test statistic
is:
7.
It can be concluded that the mean age of the student population is:
Problem C:
Use the following to answer questions 89:
A major airline company is concerned that its proportion of late arrivals has substantially
increased in the past month. Historical data shows that on the average 18% of the company
airplanes have arrived late. In a random sample of 1,240 airplanes, 310 airplanes have arrived
late. If we are conducting a hypothesis test of a single proportion to determine if the proportion
of late arrivals has increased:
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 Summer '08
 SINGER
 Normal Distribution, Regression Analysis, Standard Deviation, Variance, Statistical hypothesis testing

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