STA 2023            Practice  TEST 2                            

 

1) a) Descriptive Statistics  use ________________ or _______________ summaries to characterize a set of  data .

 

    b) Inferential Statistics use sample information to make __________________ or ____________________ about a wider range of individuals.

 

2) In a sample of 250 people, 160 answered “yes”, 90 answered “no”, to whether they own a PC. What is the proportion of the sample that answered “yes”?

(Give answer as a decimal.)                                                      ______________________

 

 

 

3) What is the standard error of the proportion in #3?    ______________________

(Show the formula, what you plug in, and round answer to the hundredths place.)

 

 

 

 

 

 

4) Find the sample size required for a study with a desired Margin of Error of 4% and a 95% confidence level. A pilot study had a standard deviation of 1.25.

(Show formula, plug-ins, and round appropriately)                     _______________________

 

 

 

 

 

 

For # 6 – 10, Find the appropriate z-score.

Your answer should say “z =   “ with each z rounded to 2 decimal places. Use a calculator screen if possible. Otherwise show the formula & your plug-ins.

 

5) m = 100 and s = 15. A random sample of 225 people has = 98.5.

 

                                                                                                ________________________

 

 

 

6) m = 100 and s = 15. An individual from a random sample of size 25 has a raw score of   

132.                                      

                                                                                                ________________________

 

 

7) p = 0.3 and a random sample has 50 out of 200.                   ________________________

 

 

 

 

 

 

 

8) A random sample of 64 subjects has  = 77 and  = 5. One student has a score of 88.

 

                                                                                                ________________________

 

 

 

 

 

 

9) A random sample of 16 data values had = 50.  The population has

m = 52 and s = 2.5.

                                                                                                _______________________

 

For # 10 – 12, tell which sampling method BEST describes each :  Stratified;  Cluster;  Systematic;  Convenience;  or Random.

 

10) A list of all stockholders is compiled and every 50th name is selected.

 

                                                                                                ________________________

                                                                                               

11) Thirty hospitals are randomly selected and all cardiac patients in each hospital are surveyed about diet and exercise.

                                                                                                ________________________

 

12) The names of the 100 U.S. senators are on individual index cards, put in a box, and

      11 are drawn to form a committee.

                                                                                                ________________________

 

 

13) What sample size is required for a proportion with a Margin of Error of 5% and a  confidence level of 90%? A pilot sample had a proportion of 0.2.

(Show the formula & “plug-ins” and round appropriately.)

 

                                                                                                ________________________

14) Given that the population of women has normally distributed weights with a mean of 143 lb. and a standard deviation of 29 lb., find the probability that if 49 different women are randomly selected, their mean weight is between 139 lb. and 148 lb.

 

                                                                                                ________________________

 

 

 

15) Given that the population of women has normally distributed weights with a mean of 143 lb. and a standard deviation of 29 lb., find the probability that a randomly selected woman has a weight between less than 150 lb.

 

                                                                                                ________________________

 

 

 

16) I.Q. scores are normally distributed with a mean of 100 and a standard deviation of 15.  If 36 people are randomly selected for an I.Q. test, find the probability that their mean I.Q. score is greater than 95.

 

                                                                                                ________________________