Question

**1. A random sample of 20 students yielded a mean of ¯x =
72 and a variance of s 2 = 16 for scores on a college placement
test in mathematics. Assuming the scores to be normally
distributed, construct a 98% confidence interval for σ 2 . Be sure
to**

**• State if the problem involves 1 population or 2
populations. If you have 2 populations, should they be paired or
not?**

**• State α.**

**• State whether you should use z, t, or χ 2 and find /
provide the appropriate value(s) from the table (or your
calculator).**

**• Find the confidence interval. Round your final values
to 3 decimals. • Write a verbal interpretation of your confidence
interval.**

**2. Problem Setup:**

**A very large study showed that aspirin reduced the rate
of heart attacks by 44%. A pharmaceutical company thinks they have
a drug that will be more effective than aspirin, and plans to do a
randomized clinical trial to test the new drug.**

**Your Questions:**

**(a) What is the null hypothesis the company will
use?**

**(b) What is their alternative hypothesis?**

**Questions 1&2**

Answer #1

1 ) The 98 % confidence interval for is :

where ,

**Required confidence interval :
**

**The problem only involves one population .**

**We are 98 % confident that the value of the population
variance will lie in the interval given by
**

2 ) To test :

Null hypothesis :

Alternative hypothesis :

A class has been given a statistics exam. In a random sample of
12 students, the test scores are 65, 73, 74, 68, 70, 74, 69, 71, 75
73 67 70, giving us the sample statistics ¯x = 70.75 and s 2 =
9.84. Assume a normal distribution of scores.
(a) Construct a 98% confidence interval for σ 2 .
(b) Construct a 98% confidence interval for σ. (Use your
information from Part A, and just state your confidence
interval.)

A sample survey asked a random sample of 1498 adult Canadians,
“Do you agree or disagree that all firearms should be registered?”
Of the 1498 people in the sample, 1282 answered either “Agree
strongly” or “Agree somewhat.” Assuming this survey can be
considered an SRS of all adult Canadians, what is the proportion of
all Canadians who agree (as described) that all firearms should be
registered?
Your solution must include the following parts, in order. Point
form is fine.
a)...

Scenario 3: t-test Analysis
Paired Samples
Statistics
Mean
N
Std. Deviation
Std. Error Mean
Pair 1
T1 Scale of student's mathematics
utility
-.0096
16021
.99040
.00782
T2 Scale of student's mathematics
utility
.0059
16021
1.00682
.00795
Paired Samples
Correlations
N
Correlation
Sig.
Pair 1
T1 Scale of student's mathematics
utility & T2 Scale of student's mathematics utility
16021
.285
.000
Paired Samples
Test
Paired Differences
t
df
Sig. (2-tailed)
Mean
Std. Deviation
Std. Error Mean
95% Confidence Interval of the...

An education minister would like to know whether students at
Gedrassi high school on average perform better at English or at
Mathematics. Denoting by μ1 the mean score for all
Gedrassi students in a standardized English exam and μ2
the mean score for all Gedrassi students in a standardized
Mathematics exam, the minister would like to get a 95% confidence
interval estimate for the difference between the means:
μ1 - μ2.
A study was conducted where many students were given...

A random sample of 22 STAT 250 students was collected and the
file size of Data Analysis 2 was recorded. The data was measured in
megabytes. The instructors of the course claim that the file size
will be different from 5 megabytes. Consider the population of all
file sizes to be right skewed. Using a= 0.01, is there sufficient
evidence to conclude that the mean file size of Data Analysis 2 is
different from 5 megabytes? Conduct a full hypothesis...

Pre-Activity Question: A random sample of 84
eighth grade students' scores on a national mathematics assessment
test has a mean score of 294. This test result prompts a state
school administrator to declare that the mean score for the
state's eighth graders on this exam is more than 285. Assume that
the population standard deviation is 31. At α = 0.10, is there
enough evidence to support the administrator's claim?
Write out the hypotheses statements below and identify the
parameter...

1.) A sample of 125 campus students who responded to a
questionnaire had a mean age of 22.0 and a standard deviation of
5.0. The mean hypothesized population age for all campus students
is 25.0.
a) Set up the hypothesis (one sample t test) for
these data at the 95% confidence level. Be sure to include the null
hypothesis and alternative hypothesis in your response.
b) Compute the t test statistic for these data.
c) Are you able to reject the...

Listed in the data table are IQ scores for a random sample of
subjects with medium lead levels in their blood. Also listed are
statistics from a study done of IQ scores for a random sample of
subjects with high lead levels. Assume that the two samples are
independent simple random samples selected from normally
distributed populations. Do not assume that the population standard
deviations are equal. Complete parts (a) and (b) below. Use a
0.10 significance level for both...

What's the deal with differences?
No unread replies.No replies.
Suppose that random samples of college freshman are selected
from two universities - 15 students from school A and 20 students
from school B. On a standardized test:
The sample from school A has an average score of 1000 with a
standard deviation of 100.
The sample from school B has an average score of 950 with a
standard deviation of 90.
(Assume the test scores came from normal distributions in...

A consumer group is testing the claim that the mean
volume of Coke in cans is greater than 12 oz. A sample of 36 cans
yielded a mean of 12.019 oz and a standard deviation of 0.11 oz.
Test the claim that the mean is actually 12 oz. Use a =
0.05.
(1) List all the information necessary for conducting
the hypothesis test and state which
test you are doing.
(2) State the null and alternative hypotheses and
whether you...

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