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mean and standard deviation

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Res 341 - Quiz for Week 4

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Find the mean for the given sample data. Unless otherwise specified, round your answer to one more decimal place
than that used for the observations.
1) 13, 20, 16, 13, 14 1)
A) 13 B) 15.2 C) 19 D) 14
Find the median for the given sample data.
2) A new business had the following monthly net gains: 2)
$6956 $3158 $1329 $7616 $7429
$1842 $3728 $8172 $5311 $5900
A) $5144.10 B) $5311.00 C) $5715.67 D) $5605.50
Find the range and standard deviation for each of the two samples, then compare the two sets of results.
3) When investigating times required for drive-through service, the following results (in seconds) 3)
were obtained.
Restaurant A 120 123 153 128 124 118 154 110
Restaurant B 115 126 147 156 118 110 145 137
A) Restaurant A: 46; 16.2
Restaurant B: 44; 16.9
It is inconclusive as to which data set has more variation.
B) Restaurant A: 44; 16.2
Restaurant B: 46; 16.9
Both measures indicate there is more variation in the data for restaurant B than the data for
restaurant A.
C) Restaurant A: 46; 16.9
Restaurant B: 44; 16.2
Both measures indicate there is more variation in the data for restaurant A than the data for
restaurant B.
D) Restaurant A: 44; 16.1
Restaurant B: 46; 16.9
Both measures indicate there is more variation in the data for restaurant B than the data for
restaurant A.
Find the indicated probability.
4) If you flip a coin three times, the possible outcomes are HHH HHT HTH HTT THH THT TTH 4)
TTT. What is the probability of getting at least two tails?
A) 12B) 18
C) 38
D) 58
1
Find the indicated probability by using the special addition rule.
5) A relative frequency distribution is given below for the size of families in one U.S. city. 5)
Size Relative frequency
2 0.457
3 0.204
4 0.192
5 0.099
6 0.030
7+ 0.018
A family is selected at random. Find the probability that the size of the family is between 2 and 5
inclusive. Round approximations to three decimal places.
A) 0.952 B) 0.396 C) 0.853 D) 0.556
Find the indicated probability.
6) The following contingency table provides a joint frequency distribution for the popular votes cast 6)
in the presidential election by region and political party. Data are in thousands, rounded to the
nearest thousand.
A person who voted in the presidential election is selected at random. Compute the probability that
the person selected was in the West and voted Republican.
A) 0.781 B) 0.196 C) 0.588 D) 0.115
Solve the problem.
7) How many ways can an IRS auditor select 6 of 12 tax returns for an audit? 7)
A) 720 B) 665,280 C) 924 D) 2,985,984
2
Find the indicated binomial probability.
8) In a certain college, 20% of the physics majors belong to ethnic minorities. If 10 students are 8)
selected at random from the physics majors, what is the probability that exactly 2 belong to an
ethnic minority?
A) 0.00007 B) 1.8 C) 0.30199 D) 0.00671
Use a table of areas to find the specified area under the standard normal curve.
9) The area that lies to the left of 1.13 9)
A) 0.8485 B) 0.8708 C) 0.8907 D) 0.1292
Use a table of areas for the standard normal curve to find the required z-score.
10) Find the z-score having area 0.09 to its left under the standard normal curve. 10)
A) -1.39 B) -1.26 C) -1.34 D) -1.45
3

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Business Statistics: Mean, Standard Deviations

I could use some help with the following. Could you please explain how you get the answer to the following questions in detail please so I can compare them to mine? I do not understand my book very well and I want to make sure I understand them correctly before I turn them in. Thank you

My first question is;

The mean starting salary for college graduates in the spring of 2004 was $36,280.
I am asking to assume the distribution of starting salaries follows the normal distribution with a standard deviation of $3,300.

What percentage of the graduates has starting salaries?

a) Between $35,000 and 45,000
b) More than $45,000
c) Between $40,000 and 45,000

My second question is;

I am ask to assume a binomial probability distribution with n=40 and (pi) =.55 and compute the following
a) The mean and standard deviation of random variable
b) The probability that X is 25 or greater
c) The probability that X is 15 or less
d) The probability that X is between 15 and 25 inclusive

My third question;

A recent study by the Greater Los Angeles Taxi Drivers Association showed that the mean fare charged for service from Hermosa Beach to the Los Angeles International Airport is $18.00 and the standard deviation is $3.50.

I am ask to select a sample of 15 fares and answer a and b. Please explain how you got your answer so I can compare it to mine.

a) What is the likelihood that the sample mean is btw $17.00 and 20.00?
b) What must you assume to make the above calculation?

My last question;
Dr. Patton is a Professor of English. Recently he counted the number of misspelled words in a group of student's essays. For his class of 40 students, the mean number of misspelled words was 6.05 and the standard deviation 2.44 per essay.

I need help constructing a 95 percent confidence interval for the mean number of misspelled words in the population of student essays.

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