Question

1. A Pew Research study regarding cell phones asked questions about cell phone experience. One growing concern is unsolicited advertising in the form of text messages. Pew asked 1150 cell phone owners, “Have you ever received unsolicited text messages on your cell pone from advertisers?” and 17% reported that they had.

a) State the parameter you want to estimate.

b) Check conditions and identify the appropriate inference method.

c) If the conditions have been met, perform the calculations for a 95% confidence interval. If conditions have not been met, state the condition that has been violated.

d) If you were able to complete c) interpret your interval in the context of the problem.

2. The 2013 International Bedroom Poll surveyed about 250 randomly sampled adult residents in each of six countries asking about their sleep habits. Sleep researchers generally report that People who regularly use their computers or laptops in the hour before trying to go to sleep are less likely to report getting a good night’s sleep..., more likely to be categorized as “sleepy”..., and more likely to drive drowsy... than their counterparts. The poll found that 128, or 51%, of 251 U.S. respondents reported using a computer, laptop, or electronic tablet in the hour before trying to go to sleep almost every night. By contrast, 162, or 65%, of 250 Japanese respondents made the same admission. What does a confidence interval say about \ the difference in sleep habits?

a) State the parameter you want to estimate.

b) Check conditions and identify the appropriate inference method.

c) If the conditions have been met, perform the calculations for a 95% confidence interval for the difference in proportions. If conditions have not been met, state the condition that has been violated.

d) If you were able to complete c) interpret your interval in the context of the problem.

3. In a March 2016 survey by Gallup of 1019 U.S. adults, 65% believe that global warming is due more to human activity than natural changes in the environment. The poll reports a margin of error of 4%. Suppose an environmental group planning a follow-up survey of voters’ opinions on global warming wants to determine a 95% confidence interval with a margin of error of no more than + 2%. How large a sample does the group need?

Answer #1

a)

p: Proportion of people received unsolicited text messages on cell pone from advertisers

b)

c)

d)

We are 95% confident that true proportion of people received unsolicited text messages on cell pone from advertisers lis in the interval (0.1482, 0.1918) or (14.82%, 19.18%).

A Pew Internet poll asked cell phone owners about how they used
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past 30 days they had used their phone while in a store to call a
friend or family member for advice about a purchase they were
considering. The poll surveyed 1003 adults living in the United
States by telephone. Of these, 462 responded that they had used
their cell phone while in a store within the last...

A recent Pew Research poll surveyed U.S. residents to ask about
their use of social media. Of the 156 respondents aged 18 to 22 who
use Facebook, 30.7% stated that they updated their Facebook status
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Is .307 the true proportion parameter p or the point estimate
p̂?
A. true proportion p
B. point estimate p̂
Compute the standard error of the sample proportion, i.e. the
standard deviation of the sample proportion.
A. 0.032
B. 0.043...

A company that produces cell phones claims its standard phone
battery lasts longer on average than other batteries in the market.
To support this claim, the company publishes an ad reporting the
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their batteries last at least 35 hours. To investigate this claim,
a consumer advocacy group asked the company for the raw data,
which are shown to the right. Find a 95 % confidence interval and
state your conclusion....

1. When constructing a confidence interval to estimate a
population proportion, what affects the size of the margin of
error?
A. The sample size
B. The sample proportion
C. The confidence level
D. All of the above affect the size of the margin of error
E. None of the above affect the size of the margin of error
2. What percentage of couples meet through online dating
apps? A survey of a random sample of couples finds that 12% say...

During the first 20 games of a basketball season, one player
made 34 of her 40 free throws. A teammate made 35 of her 44 free
throws. Assume that all conditions for running two proportion
inference procedures have been met - even though this is
questionable.
a) determine the two different standard errors you would use for
the following procedures.
-Confidence interval
-test of significance
b) The 95% confidence interval for the difference in the two
proportions (player-teammate) is about...

These next few questions ask about confidence intervals.
a) Bruce Wayne studies. A random sample of data on a categorical
variable and calculates a 95% confidence interval for the
population proportion to be (0.546, 0.674). Determine what the
sample proportion must have been, and explain why.
b) Suppose Clark and Lois plan to collect separate random
samples, with Clark using a sample size of 500 and Lois using a
sample size of 1500. Brad plans to construct a 99% confidence...

Part 1 Hypothesis Test and Confidence Interval from 1 sample
Test ONE claim about a population parameter by collecting your
own data or using our class survey data. Include your
written claim, hypothesis in both
symbolic and written form, relevant statistics
(such as sample means, proportions etc.), test
statistic, p-value (or critical value),
conclusion, and interpretation of
your conclusion in the context of your claim. Use a 0.05
significance level.
You will also construct a 95% confidence interval
estimate of...

You are interested in testing Chips Ahoy’s claim that
bags of Chips Ahoy cookies contain more than 1000 chips, on
average. Suppose you have an SRS of 62 bags of cookies and find
that the sample mean is 1022 chips. The sample standard deviation s
is 94.2 chips. There are no outliers or signs of strong skew. (a)
Check the conditions for inference. Are the data from an SRS? Are
the sample size and distributional requirements met? Specify why or...

1) In 2003, Motorola released a cell phone, the RAZR, that was a
breakthrough in design and major hit with customers. The engineers,
designers, and marketers involved came from all over the company.
They made decisions independently, including developing the project
objectives, the project budget, the project schedule and assigning
tasks. The project was finished ahead of schedule and under
budget.
A. This demonstrates that teams must contain mostly creative
professionals to succeed
B. This shows the value of autonomy...

1. Find the area under the standard normal curve (round to four
decimal places)
a. To the left of z=1.65
b. To the right of z = 0.54
c. Between z = -2.05 and z = 1.05
2. Find the z-score that has an area of 0.23 to its right.
3. The average height of a certain group of children is 49
inches with a standard deviation of 3 inches. If the heights are
normally distributed, find the probability that a...

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