Question

Math 133: 9.4 Worksheet #2 Name: Section: 9.4: Sample Size; More on Confidence Intervals 1. A researcher wants to construct a 99.5% confidence interval for the proportion of adults in the U.S. that believe civilians need to have the power to sue police officers for excessive force. NOTE: Use 3 decimal places for z-score. (Source) a. Estimate how many people need to be surveyed if no prior estimate of p is available and the researcher wants to be within 3% of the true proportion. (Give formula, substitution, and result) b. A Pew Research poll taken in June 2020 estimates this proportion to be 0.66. Using this estimate, now how many people are needed to be surveyed (staying with the C-level and margin of error from part a)? (Give formula, substitution, and result) c. The sample size from part b would be lowered but the C-level remained the same. (Circle one) if the margin of error was Smaller Larger The same Cannot be determined 2. In October 2012, vice-presidential candidates Joe Biden and Paul Ryan had a televised debate. Afterwards two different polls were conducted asking "who won the debate?" Which survey is a better/more reliable measure of the "winner" of the debate? Explain. Who won the Poll #1: 431 random de bate? people Poll #2: 191897 people online Joe Biden 50% 46% Paul Ryan 31% 48% Neither 19% 6%

          Math 133: 9.4 Worksheet #2
Name:
Section:
9.4: Sample Size; More on Confidence Intervals
1. A researcher wants to construct a 99.5% confidence interval for the proportion of adults in
the U.S. that believe civilians need to have the power to sue police officers for excessive
force. NOTE: Use 3 decimal places for z-score. (Source)
a. Estimate how many people need to be surveyed if no prior estimate of p is available and
the researcher wants to be within 3% of the true proportion. (Give formula, substitution,
and result)
b. A Pew Research poll taken in June 2020 estimates this proportion to be 0.66. Using this
estimate, now how many people are needed to be surveyed (staying with the C-level
and margin of error from part a)? (Give formula, substitution, and result)
c. The sample size from part b would be
lowered but the C-level remained the same. (Circle one)
if the margin of error was
Smaller
Larger
The same
Cannot be determined
2. In October 2012, vice-presidential candidates Joe Biden and Paul Ryan had a televised
debate. Afterwards two different polls were conducted asking "who won the debate?"
Which survey is a better/more reliable measure of the "winner" of the debate? Explain.
Who won the Poll #1: 431 random
de bate?
people
Poll #2: 191897
people online
Joe Biden
50%
46%
Paul Ryan
31%
48%
Neither
19%
6%

Math 133: 9.4 Worksheet #2
Name:
Section:
9.4: Sample Size; More on Confidence Intervals
1. A researcher wants to construct a 99.5% confidence interval for the proportion of adults in
the U.S. that believe civilians need to have the power to sue police officers for excessive
force. NOTE: Use 3 decimal places for z-score. (Source)
a. Estimate how many people need to be surveyed if no prior estimate of p is available and
the researcher wants to be within 3% of the true proportion. (Give formula, substitution,
and result)
b. A Pew Research poll taken in June 2020 estimates this proportion to be 0.66. Using this
estimate, now how many people are needed to be surveyed (staying with the C-level
and margin of error from part a)? (Give formula, substitution, and result)
c. The sample size from part b would be
lowered but the C-level remained the same. (Circle one)
if the margin of error was
Smaller
Larger
The same
Cannot be determined
2. In October 2012, vice-presidential candidates Joe Biden and Paul Ryan had a televised
debate. Afterwards two different polls were conducted asking "who won the debate?"
Which survey is a better/more reliable measure of the "winner" of the debate? Explain.
Who won the Poll #1: 431 random
de bate?
people
Poll #2: 191897
people online
Joe Biden
50%
46%
Paul Ryan
31%
48%
Neither
19%
6%

Added by Brendan A.

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