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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

how can l calculate G. M from the following size 125 133 141 173 182 frequency 7 5 4 1 3
Stancy Reply
how they find mean population
Joy Reply
parts of statistics
Edwin Reply
what is a mean?
Onele Reply
given the sequence 128,64,32 find the 12th term of the sequence
Shehu Reply
12th number is 0.0625
Thangarajan
why do we use summation notation to represent set of observations
MICHAEL Reply
what is the potential outlier ?
Anik Reply
A pharmaceutical company claims that their pain reliever capsule is 70% effective. But a clinical test on this capsule showed 65 out of 100 effectiveness
jelly Reply
Part of statistics
charls Reply
how to find mean population
Dawit Reply
what is data value
Ravneet Reply
what is relative frequency
Adeyemi Reply
liner regression analysis
Swathy Reply
Proper definition of outlier?
Sumbal Reply
Extraordinary observation (too distant, high, low etc)
Petr Reply

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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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