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Use the following information to answer the next three exercises: A community college offers classes 6 days a week: Monday through Saturday. Maria conducted a study of the students in her classes to determine how many days per week the students who are in her classes come to campus for classes. In each of her 5 classes she randomly selected 10 students and asked them how many days they come to campus for classes. Each of her classes are the same size.The results of her survey are summarized in [link] .

Number of Days on Campus Frequency Relative Frequency Cumulative Relative Frequency
1 2
2 12 .24
3 10 .20
4 .98
5 0
6 1 .02 1.00

20 . Combined with convenience sampling, what other sampling technique did Maria use?

  1. simple random
  2. systematic
  3. cluster
  4. stratified

21 . How many students come to campus for classes four days a week?

  1. 49
  2. 25
  3. 30
  4. 13

22 . What is the 60 th percentile for the this data?

  1. 2
  2. 3
  3. 4
  4. 5

Use the following information to answer the next two exercises: The following data are the results of a random survey of 110 Reservists called to active duty to increase security at California airports.

Number of Dependents Frequency
0 11
1 27
2 33
3 20
4 19

23 . Construct a 95% confidence interval for the true population mean number of dependents of Reservists called to active duty to increase security at California airports.

  1. (1.85, 2.32)
  2. (1.80, 2.36)
  3. (1.97, 2.46)
  4. (1.92, 2.50)

24 . The 95% confidence interval above means:

  1. Five percent of confidence intervals constructed this way will not contain the true population aveage number of dependents.
  2. We are 95% confident the true population mean number of dependents falls in the interval.
  3. Both of the above answer choices are correct.
  4. None of the above.

25 . X ~ U (4, 10). Find the 30 th percentile.

  1. 0.3000
  2. 3
  3. 5.8
  4. 6.1

26 . If X ~ Ex p(0.8), then P ( x < μ ) = __________

  1. 0.3679
  2. 0.4727
  3. 0.6321
  4. cannot be determined

27 . The lifetime of a computer circuit board is normally distributed with a mean of 2,500 hours and a standard deviation of 60 hours. What is the probability that a randomly chosen board will last at most 2,560 hours?

  1. 0.8413
  2. 0.1587
  3. 0.3461
  4. 0.6539

28 . A survey of 123 reservists called to active duty as a result of the September 11, 2001, attacks was conducted to determine the proportion that were married. Eighty-six reported being married. Construct a 98% confidence interval for the true population proportion of reservists called to active duty that are married.

  1. (0.6030, 0.7954)
  2. (0.6181, 0.7802)
  3. (0.5927, 0.8057)
  4. (0.6312, 0.7672)

29 . Winning times in 26 mile marathons run by world class runners average 145 minutes with a standard deviation of 14 minutes. A sample of the last ten marathon winning times is collected. Let x = mean winning times for ten marathons. The distribution for x is:

  1. N ( 145 , 14 10 )
  2. N ( 145 , 14 )
  3. t 9
  4. t 10

30 . Suppose that Phi Beta Kappa honors the top one percent of college and university seniors. Assume that grade point means (GPA) at a certain college are normally distributed with a 2.5 mean and a standard deviation of 0.5. What would be the minimum GPA needed to become a member of Phi Beta Kappa at that college?

  1. 3.99
  2. 1.34
  3. 3.00
  4. 3.66

Questions & Answers

What is the variances of 568
Helen Reply
what u asking...
friend
what variance would have a single value..?
friend
variance happened only in a group of values..
friend
if we have a group of values...1st we find its average..ie..'mean'..then we calculate each value's difeerence from the mean..then we will square each 'difference value'.then we devide total of sqared value by n or n-1..that is what variance...
friend
What is the variances of 258
Helen Reply
66,564
Mampy
what is the sample size if the degree of freedom is 25?
Arthur Reply
26..
friend
25
Tariku
27
Tariku
degrees of freedom may differ with respect to distribution...so tell which distribution you have selected...?
friend
my distribution is 27
Tariku
how to understand statistics
Edwin Reply
you are working for a bank.The bank manager wants to know the mean waiting time for all customers who visit this bank. she has asked you to estimate this mean by taking a sample . Briefly explain how you will conduct this study. assume the data set on waiting times for 10 customers who visit a bank. Then estimate the population mean. choose your own confidence level.
Halpha Reply
what marriage for 10 years
Ambaye Reply
fit a least square model of y on x ? what is the regression coefficient ? x : 2 3 6 8 9 10 y : 5 6 7 10 8 11
Nayab Reply
how can we find the expectation of any function of X?
Jennifer
I've been using this app for some time now. I'm taking a stats class in college in spring and I still have no idea what's going on. I'm also 55 yrs old. Is there another app for people like me?
Tamala
Serious
Hamza
yes I am. it's been decades since I've been in school.
Tamala
who are u
zaheer
is there a private chat we can do
Tamala
hello how can I get PDF of solutions introduction mathematical statistics ( fourth education) who can help me
ahssal
can anyone help me
Halim
what is probability
zaheer Reply
simply probability means possibility.. definition:Probability is a measure of the likelihood of an event to occur.
laraib
fit a least square model of y on x ? what is the regression coefficient ? x : 2 3 6 8 9 10 y : 5 6 7 10 8 11
Nayab
classification of data by attributes is called
Yamin Reply
qualitative classification
talal
tell me details about measure of Dispersion
Halim
Following data provided Class Frequency less than 10 10-20 5 15 10-30 25 12 40 and above Which measure of central tendency would you compute and why?
Nija Reply
a box contains a few red and a few blue balls.one ball is drawn randomly find the probability of getting a red ball if we know that there are 30 red and 40 blue balls in the box
harish Reply
3/7
RICH
Total=30+40=70 P(red balls) =30/70 Therefore the answer is 3/7
Anuforo
define transport statistical unit
Dennis Reply
describe each transport statistical unit
Dennis
explain uses of each transport statistical unit
Dennis
identify various transport statistical units with their example
Dennis
I didn't understand about Chi- square.
Esayas Reply
explain the concept of data analysis and data processing
Kim Reply
the following data represent the number of pop up advertisement received by 10 families during the past month.calculate the mean number of advertisement received by each family during month.43,37,35,30,41,23,33,31,16,21
ejaz Reply
mean=43+37+35+30+41+23+33+31+16/10 =310/10 =31
Anuforo
43+37+35+30+41+23+33+31+16 divided by 10 =310/10 =31
Anuforo
=310/10 =31
Anuforo

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Source:  OpenStax, Introductory statistics. OpenStax CNX. May 06, 2016 Download for free at http://legacy.cnx.org/content/col11562/1.18
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