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
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.
________________________