STAT 211 EXAM 5 QUESTIONS AND 100%
CORRECT ANSWERS!!
A research company polled a random sample of 989 teens about Internet use. 50% of those
teens reported that they had misrepresented their age online to gain access to websites and
online services.
a). Explain the meaning of p=0.50 in that context of this situation.
b). Calculate the standard error of p
c) Explain what this standard error means in the context of this situation.
ch 16-17 HW #1
A research company polled a random sample of 799 U.S. teens about Internet use. 49% of
those teens reported that they had misrepresented their age online to gain access to
websites and online services
a). Interpret the interval in this context.
b). Explain the measuring of "95% confident" in this context.
ch 16-17 HW #2
Several factors are involved in the creation of a confidence interval. Among them are the
sample size, the level of confidence, and the margin of error. Which statements are true?
a). For a given sample size, lower confidence means a larger margin of error. Is this
statement true?
b). For a special confidence level, larger sample provide smaller margins of error samples
provide smaller margin of error. Is the statement true?
c)
d)
ch 16-17 HW #3
Of 515 broiler chickens purchased from various kinds of food stores in different regions of
a country and tested for types of bacteria that cause food-borne illnesses, 36% were
infected with a particular bacteremia.
a). what is the 90% confidence interval?
,b). what does the confidence interval say about chicken sold in the country?
c) is the government spokesperson's criticism valid?
ch 16-17 hw 4
A consumer advocacy group published a study of labeling of seafood sold in three U.S.
states. The study found 11 of the 26 "red snapper" packages tested were a different kind of
fish. Assume that the study used a simple random sample.
a) are the conditions for creating a confidence interval satisfied? explain.
b). construct a 95% confidence interval for the proportion of "red snapper" packages that
were a different kind of fish
c) explain what the confidence interval from part b says about "red snapper" sold in these
three states.
ch 16-17 hw 5
An insurance company checks police records on 594 accidents selected at random and
notes that teenagers were at the wheel in 89 of them.
a) construct the 95% confidence interval for the percentage of all auto accidents that
involve teenage drivers.
b). explain what your interval means.
c) explain what "95% confidence" means
d) a politician urges tighter restriction on drivers' licenses issued to teens says, "In one of
every five auto accidents, a teenager is behind the wheel." Does the confidence interval
contradict this statement?
ch 16-17 hw 6
A reproductive clinic reported 45 live births to 208 women under age age of 40 who had
previously been unable to conceive.
a) find a 90% confidence interval for the success rate at this clinic.
b) interpret your interval in this context
c) explain what "90% confidence" means
d) Do these data refute the clinic's claim of a 25% success rate? Explain.
, ch 16-17 hw 7
In a confidence interval, the amount we reach out on either side of the sample proportion is
called the MARGIN OF ERROR.
ch 16-17 hw 8
To decrease the margin of error without decreasing the level of confidence, the sample size
needs to be INCREASED
CH 16-17 HW 9
which of these statements correctly interprets what it means to be "95% confident"?
ch 16-17 HW 10
A mayor is concerned about his "negatives", that is, the percentages of city residents who
express disapproval of his job performance. His political committee pays for a series of TV
ads, hoping that they can keep the negatives below 40%. They will use follow up polling to
assess the ads effectiveness. Write the null and alternative hypothesis you would use to test
the situation below
ch 16-17 HW 11
a very large study showed that aspirin reduced the rate of first heart attacks by 31%. A
phamaceutical company thinks it has a drug that will....
a) the P-value from the hypothesis test was 0.47. what do you conclude?
what would you have concluded if the p-value had been 0.002?
ch 16-17 hw 12
According to the recent census, 18% of the people in the united States are of Hispanic
origin. One county supervisor believes her country has a different proportion of Hispanic
people than the nation as a whole. she looks at their most recent survey data, which was a
random sample of 476 country residents, and found that 50 of those surveyed are of the
Hispanic origin.
ch 16-17 hw 13
CORRECT ANSWERS!!
A research company polled a random sample of 989 teens about Internet use. 50% of those
teens reported that they had misrepresented their age online to gain access to websites and
online services.
a). Explain the meaning of p=0.50 in that context of this situation.
b). Calculate the standard error of p
c) Explain what this standard error means in the context of this situation.
ch 16-17 HW #1
A research company polled a random sample of 799 U.S. teens about Internet use. 49% of
those teens reported that they had misrepresented their age online to gain access to
websites and online services
a). Interpret the interval in this context.
b). Explain the measuring of "95% confident" in this context.
ch 16-17 HW #2
Several factors are involved in the creation of a confidence interval. Among them are the
sample size, the level of confidence, and the margin of error. Which statements are true?
a). For a given sample size, lower confidence means a larger margin of error. Is this
statement true?
b). For a special confidence level, larger sample provide smaller margins of error samples
provide smaller margin of error. Is the statement true?
c)
d)
ch 16-17 HW #3
Of 515 broiler chickens purchased from various kinds of food stores in different regions of
a country and tested for types of bacteria that cause food-borne illnesses, 36% were
infected with a particular bacteremia.
a). what is the 90% confidence interval?
,b). what does the confidence interval say about chicken sold in the country?
c) is the government spokesperson's criticism valid?
ch 16-17 hw 4
A consumer advocacy group published a study of labeling of seafood sold in three U.S.
states. The study found 11 of the 26 "red snapper" packages tested were a different kind of
fish. Assume that the study used a simple random sample.
a) are the conditions for creating a confidence interval satisfied? explain.
b). construct a 95% confidence interval for the proportion of "red snapper" packages that
were a different kind of fish
c) explain what the confidence interval from part b says about "red snapper" sold in these
three states.
ch 16-17 hw 5
An insurance company checks police records on 594 accidents selected at random and
notes that teenagers were at the wheel in 89 of them.
a) construct the 95% confidence interval for the percentage of all auto accidents that
involve teenage drivers.
b). explain what your interval means.
c) explain what "95% confidence" means
d) a politician urges tighter restriction on drivers' licenses issued to teens says, "In one of
every five auto accidents, a teenager is behind the wheel." Does the confidence interval
contradict this statement?
ch 16-17 hw 6
A reproductive clinic reported 45 live births to 208 women under age age of 40 who had
previously been unable to conceive.
a) find a 90% confidence interval for the success rate at this clinic.
b) interpret your interval in this context
c) explain what "90% confidence" means
d) Do these data refute the clinic's claim of a 25% success rate? Explain.
, ch 16-17 hw 7
In a confidence interval, the amount we reach out on either side of the sample proportion is
called the MARGIN OF ERROR.
ch 16-17 hw 8
To decrease the margin of error without decreasing the level of confidence, the sample size
needs to be INCREASED
CH 16-17 HW 9
which of these statements correctly interprets what it means to be "95% confident"?
ch 16-17 HW 10
A mayor is concerned about his "negatives", that is, the percentages of city residents who
express disapproval of his job performance. His political committee pays for a series of TV
ads, hoping that they can keep the negatives below 40%. They will use follow up polling to
assess the ads effectiveness. Write the null and alternative hypothesis you would use to test
the situation below
ch 16-17 HW 11
a very large study showed that aspirin reduced the rate of first heart attacks by 31%. A
phamaceutical company thinks it has a drug that will....
a) the P-value from the hypothesis test was 0.47. what do you conclude?
what would you have concluded if the p-value had been 0.002?
ch 16-17 hw 12
According to the recent census, 18% of the people in the united States are of Hispanic
origin. One county supervisor believes her country has a different proportion of Hispanic
people than the nation as a whole. she looks at their most recent survey data, which was a
random sample of 476 country residents, and found that 50 of those surveyed are of the
Hispanic origin.
ch 16-17 hw 13
