Question
In: Statistics and Probability
In a school district, all sixth grade students take the same standardized test. The superintendant of...
In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 25 scores from all of the students who took the test. She sees that the mean score is 170 with a standard deviation of 4.0774. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 13. Is there evidence that the standard deviation of test scores has decreased at the α=0.025 level? Assume the population is normally distributed.
Step 2 of 5 :
Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places.
Step 3 of 5: Determine the value of the test statistic. Round your answer to three decimal places.
Step 4 of 5: Make the decision.
Step 5 of 5: What is the conclusion?
Solutions
orchestra answered 2 years agoRelated Solutions
In a school district, all sixth grade students take the same standardized test. The superintendant of...
In a school district,
all sixth grade students take the same standardized test. The
superintendant of the school district takes a random sample of 2323
scores from all of the students who took the test. She sees that
the mean score is 147147 with a standard deviation of
18.963118.9631. The superintendant wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 1212. Is there evidence that the standard
deviation of test scores has...
In a school district, all sixth grade students take the same standardized test. The superintendant of...
In a school district, all sixth grade students take the same
standardized test. The superintendant of the school district takes
a random sample of 22 scores from all of the students who took the
test. She sees that the mean score is 160 with a standard deviation
of 28.2396. The superintendant wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 28. Is there evidence that the standard
deviation of test scores has...
In a school district, all sixth grade students take the same standardized test. The superintendant of...
In a school district, all sixth grade students take the same
standardized test. The superintendant of the school district takes
a random sample of 26 scores from all of the students who took the
test. She sees that the mean score is 101 with a standard deviation
of 10.1793. The superintendant wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 21. Is there evidence that the standard
deviation of test scores has...
In a school district, all sixth grade students take the same standardized test. The superintendant of...
In a school district, all sixth grade students take the same
standardized test. The superintendant of the school district takes
a random sample of 29 scores from all of the students who took the
test. She sees that the mean score is 167 with a standard deviation
of 11.4238. The superintendant wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 18. Is there evidence that the standard
deviation of test scores has...
In a school district, all sixth grade students take the same standardized test. The superintendant of...
In a school district, all sixth grade students take the same
standardized test. The superintendant of the school district takes
a random sample of 25 scores from all of the students who took the
test. She sees that the mean score is 139 with a standard deviation
of 16.5865. The superintendant wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 29. Is there evidence that the standard
deviation of test scores has...
In a school district, all sixth grade students take the same standardized test. The superintendent of...
In a school district, all sixth grade students take the same
standardized test. The superintendent of the school district takes
a random sample of 26 scores from all of the students who took the
test. She sees that the mean score is 130 with a standard deviation
of 7.2344. The superintendent wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 16. Is there evidence that the standard
deviation of test scores has...
IN SAS: The local school district wants to survey all sixth-grade students and their school aged...
IN SAS:
The local school district wants to survey all sixth-grade
students and their school aged siblings. There are three surveys to
do: one for the sixth graders, one for their younger siblings, and
one for their older siblings. You are to help the district office
to administer the survey. The school district has data on the
students to facilitate the survey. The SAS data set called
SCHOOLSURVEY contains data for all sixth graders in the three
middle schools in...
A school district has a standardized test that it uses to sort students into magnet schools,...
A school district has a standardized test that it uses to
sort students into magnet schools, where the test is on a 200-point
scale. The superintendent is looking to determine whether male and
female students have approximately equal scores on the test. The
scores for a random sample of 20 male students and 20 female
students are recorded. Assume that the population variances of
scores for male and female students are equal and that the scores
are normally distributed for...
The following table shows the number of fifth and sixth grade teachers in a school district...
The following table shows the number of fifth and sixth grade
teachers in a school district and the number of students in each of
those grades. The number of teachers for each of the grade levels
was determined by using the Huntington-Hill apportionment method.
The district has decided to hire a new teacher for either the fifth
or sixth grade.
Number of
teachers
Number of
students
Fifth grade
19
607
Sixth grade
23
739
(a) Use the apportionment principle to...
A standardized test is given to a sixth grade class. Historically, the test scores have had...
A standardized test is given to a sixth grade class.
Historically, the test scores have had a standard deviation of 21.
The superintendent believes that the standard deviation of
performance may have recently changed. She randomly sampled 30
students and found a mean of 160 with a standard deviation of
21.3846. Is there evidence that the standard deviation of test
scores has increased at the α=0.025 level? Assume the population is
normally distributed.
Step 1 of 5: State the hypotheses...
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