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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

binomial distribution tends to normal distribution
Murali Reply
if sample size n very large and probability tends to 0.5 if these both conditions are satisfied by binomial distribution it would tends to normal distribution
n tends to infinite i.e large Probability tends to 0 i.e indefinitely small. np = lamda
the above is poison to Bin
no of trails n tends to indefinitely large..i.e infine neither p nor q is very small Then bin tends to normal
if the death of of the snow is my yard is normally distributed with the m is equals to 2.5 and what is the probability that a randomly chosen location with have a no that between 2.25 and 2.76
Sakshi Reply
why Statistics so hard
ho geya solve
it's not hard
it is hard 😭
it's just need to be concentrate
exactly..... concentration is very important
rewrite the question
what is the true statement about random variable?
Henna Reply
A consumer advocate agency wants to estimate the mean repair cost of a washing machine. the agency randomly selects 40 repair cost and find the mean to be $100.00.The standards deviation is $17.50. Construct a 90% confidence interval for the mean.
Deshah Reply
pls I need understand this statistics very will is giving me problem
Bolanle Reply
Sixty-four third year high school students were given a standardized reading comprehension test. The mean and standard deviation obtained were 52.27 and 8.24, respectively. Is the mean significantly different from the population mean of 50? Use the 5% level of significance.
Daryl Reply
how do I find the modal class
Bruce Reply
look for the highest occuring number in the class
the probability of an event occuring is defined as?
James Reply
The probability of an even occurring is expected event÷ event being cancelled or event occurring / event not occurring
what is simple bar chat
Toyin Reply
Simple Bar Chart is a Diagram which shows the data values in form of horizontal bars. It shows categories along y-axis and values along x-axis. The x-axis displays above the bars and y-axis displays on left of the bars with the bars extending to the right side according to their values.
statistics is percentage only
Moha Reply
the first word is chance for that we use percentages
it is not at all that statistics is a percentage only
I need more examples
Luwam Reply
how to calculate sample needed
Jim Reply
mole of sample/mole ratio or Va Vb
how to I solve for arithmetic mean
Joe Reply
Yeah. for you to say.
how do I solve for arithmetic mean
Joe Reply
please answer these questions
add all the data and divide by the number of data sets. For example, if test scores were 70, 60, 70, 80 the total is 280 and the total data sets referred to as N is 4. Therfore the mean or arthritmatic average is 70. I hope this helps.
*Tan A - Tan B = sin(A-B)/CosA CosB ... *2sinQ/Cos 3Q = tan 3Q - tan Q
Ibraheem 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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