CUNY DATA205 Exam 2 Latest 2019 JULY Question # 00603540 Subject: Education Due on: 08/09/2019 Posted On: 08/09/2019 08:28 AM Tutorials: 1 Rating: 4.7/5

DATA205 Introductory Analytics (QC)

Exam 2

Question 1A
defining characteristic of the normal curve is that it is

Answers:

a.
theoretical.

b.
perfectly nonsymmetrical.

c.
positively skewed.

d.
negatively skewed.

Question 2A
sample selected according to the principle of EPSEM is extremely likely to be

Answers:

a.
inaccurate.

b. biased.

c. large.

d. representative.

Question
3By definition, the normal curve is

Answers:

a.
empirical.

b.
positively skewed.

c.
negatively skewed.

d. symmetrical.

Question
4By the theorems presented in the text, we know that the mean of a sampling
distribution of sample means will be

Answers:

a. close to
the value of the sample mean.

b.
representative of the entire population.

c. the same as the population mean.

d. between
the population and sample means in value.

Question
5Converting scores into Z scores standardizes the original distribution to
units of the

Answers:

a. median.

b.
percentage.

c. mean.

d. standard deviation.

Question
6In systematic random sampling, the researcher randomly selects

Answers:

a. cases
according to their scores.

b. the first case and every kth case
thereafter.

c. every
other case.

d. cases
following any systematic pattern.

Question
7In the normal curve, the mean is?

Answers:

a. ?equal
to the median and mode.

b. greater
than the mode.

c. ?greater
than the median.

d. ?less
than the median.

Question
8On all normal curves the area between the mean and ± 1 standard deviation will
be

Answers:

a. about
68% of the total area.

b. about
34% of the total area.

c. 50% of
the total area.

d. 99.9% of
the total area.

Question
9Social scientists gather data from samples instead of populations because

Answers:

a. samples
are much larger and more complete.

b. samples
are more meaningful and interesting.

c. samples
are more trustworthy.

d. populations are often too large to test.

Question
10The shape of the sampling distribution of sample means can be assumed to be
normal when N is

Answers:

a. a large
percentage of the population.

b. at least
twice the value of the population standard deviation.

c. 100 or more.

d. any
number as long as you know the value of the population mean.

Question
11Unless a sample is __________, it cannot be used to make accurate
generalizations to a population.

Answers:

a.
representative

b. very
small

c.
stratified

d. very
large

Question
12The most commonly used confidence level is

Answers:

a. 90.5%

b. 99.5%

c. 95%

d. 90%

Question
13A confidence level of 99% is the same as an alpha level of

Answers:

a. 0.001

b. 0.10

c. 0.05

d. 0.01

Question 14

All other
things being equal, larger sample will cost more to process

Answers: a. and will always produce narrower
confidence intervals.

b. but will
not necessarily have narrower confidence intervals.

c. but will
produce more precise intervals if the confidence level is low.

d. and will
always produce wider confidence intervals.

Question
15The width of an interval estimate can be controlled by

Answers:

a. changing
the confidence level.

b. changing
the alpha level.

c. changing
the sample size.

d. Any of the above

Question
16A one-tailed test of significance could be used whenever

Answers:

a. the
researcher feels like it.

b. the researcher can predict a direction for
the difference.

c. the null
hypothesis is thought to be true.

d. the
alpha level exceeds 0.10.

Question 17Do
sex education classes and free clinics that offer counseling for teenagers
reduce the number of pregnancies among teenagers? The appropriate test of this
hypothesis would be

Answers:

a. a
one-tailed test.

b.
participant observation.

c. a
two-tailed test.

d.
cross-sectional.

Question 18
If we reject a null hypothesis which is in fact true, we

Answers:

a. should
have used a one-tailed test.

b. have made a Type I error.

c. have
made a Type II error.

d. have
made a correct decision.

Question 19
In most cases, a researcher sets out to?

Answers:

a. ?prove
the null hypothesis.

b. ?disprove the null hypothesis.

c. ?disprove
the research hypothesis.

d. ?prove
the research hypothesis.

Question 20
In terms of hypothesis testing, “significance” refers to the?

Answers:

a.
?difference between an independent and dependent variable.

b.
?difference between the two independent variables.

c.
?difference between the sample and population values.

d.
?difference between our observed and our predicted outcomes.

Question 21
A school’s athletics department only has enough money to fund awards for its
top two athletes. The awards will be distributed based on the relative
performance of each player within their sport. The head of the athletics
department asks the team coaches for information on the most valuable players
are on each sports team.

Sarah is
the top player on the bowling team, she consistently bowls a score of 220. The mean bowling score in the conference is
187 with a standard deviation of 15. Her
z-score is +2.20

Billy is
the highest scoring player on the soccer team.
He had 25 goals this season. The conference average (among leading
scorers) was 11 goals with a standard deviation of 7. His z-score is +2.00

Tom is the
player with the most runs scored on the baseball team. He scored 29 runs this season. The conference
average runs scored is 15 with a standard deviation of 6. His z-score is +2.33

Based on
their individual performances, who will NOT get the money? Explain your choice.

Question 22
How would you find an area that is between two positive z-scores on the normal
curve?

Question 23Why
can’t a random sample mean be directly compared to a population mean to see if
they are different?

Question 24What
happens to the standard error of a sample mean when you increase the N?

Question
25A researcher reports that using 99% confidence her finding is “statistically
significant.”

What
statistical decision did she make?

What
percent of all possible samples would have the same conclusion?

What is the
probability that her conclusion is incorrect?

Question 26The
Monitoring the Future (MTF) project began in 1975. The MTF studies changes in
the beliefs, attitudes, and behavior of young people in the United States. The
survey samples 12th grade students from across the United States.

Below is
output for GPA from the most recent sample of 12th graders:

What is the
point estimate of the population mean based on the output above?

What
confidence level was used in this analysis?

Question 27A
boat manufacturing company wants to know how long people own their boats before
purchasing a new one. A random sample of
160 boat owners showed that, on average, they own a boat for 8.5 years, with a
standard deviation of 3.55 years, before they purchase a new boat. Using a 99% confidence level, what is the
mean length of boat ownership for all boat owners?

(Show all
work below including formula(s) and calculation(s))

Question 28In
a random sample of 23 private school teachers in Queens County, the average
teaching experience is 8.4 years with a standard deviation of 3.02 years. In the State of New York, private school
teachers have a mean of 9.6 years of teaching experience. Are the private school teachers in Queens
County significantly less experienced than all private school teachers in New
York State?

(Show all work below including formula(s) and
calculation(s))

Question 29
An auto manufacturer followed the repair records of the cars manufactured in a
new plant and found that they had an average of 7 repairs with a standard
deviation of 4 before the warranties expired. Assume that the number of repairs
is normally distributed.

What
percent of the cars from this plant would have over 10 repairs?

If 450 cars
of the cars sold were manufactured at this plant, how many of them would have
over 10 repairs?