Question

If the quality of teaching is similar in a school, the scores on a standardized test will have a standard deviation of 11. The superintendent wants to know if there is a disparity in teaching quality, and decides to investigate whether the standard deviation of test scores has changed. She samples 21 random students and finds a mean score of 176 with a standard deviation of 5.0654. 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. (reject or not reject null)

Step 5 of 5: What is the conclusion? (sufficient or insufficient info)

Answer #1

If the quality of teaching is similar in a school, the scores on
a standardized test will have a standard deviation of 19. The
superintendent wants to know if there is a disparity in teaching
quality, and decides to investigate whether the standard deviation
of test scores has changed. She samples 22 random students and
finds a mean score of 110 with a standard deviation of 16.709. Is
there evidence that the standard deviation of test scores has
decreased at...

If the quality of teaching is similar in a school, the scores on
a standardized test will have a standard deviation of 27 . The
superintendent wants to know if there is a disparity in teaching
quality, and decides to investigate whether the standard deviation
of test scores has changed. She samples 25 random students and
finds a mean score of 161 with a standard deviation of 13.2914 . Is
there evidence that the standard deviation of test scores has...

If the quality of teaching is similar in a school, the scores on
a standardized test will have a standard deviation of 1616. The
superintendent wants to know if there is a disparity in teaching
quality, and decides to investigate whether the standard deviation
of test scores has changed. She samples 2626 random students and
finds a mean score of 166166 with a standard deviation of
17.982217.9822. Is there evidence that the standard deviation of
test scores has increased at...

PLEASE DOUBLE CHECK ANSWER IS CORRECT & DON'T USE
HANDWRITTEN ANSWERS. THANK YOU!
If the quality of teaching is similar in a school, the scores on
a standardized test will have a standard deviation of 16. The
superintendent wants to know if there is a disparity in teaching
quality, and decides to investigate whether the standard deviation
of test scores has changed. She samples 26 random students and
finds a mean score of 186 with a standard deviation of 7.276....

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 121 with a standard deviation
of 14.3688. The superintendant wants to know if the standard
deviation has changed this year. Previously, the population
standard deviation was 24. Is there evidence that the standard
deviation of test scores has...

A standardized test is given to a sixth grade class and a ninth
grade class. The superintendent believes that the variance in
performance from the sixth grade class is different than the
variance in performance from the ninth grade class. The sample
variance of a sample of 16 test scores from the sixth grade class
is 23.64. The sample variance of a sample of 10 test scores from
the ninth grade class is 14.9. Test the claim using a 0.05...

A standardized test is given to an eighth grade class and a
ninth grade class. The superintendent believes that the variance in
performance from the eighth grade class is smaller than the
variance in performance from the ninth grade class. The sample
variance of a sample of 15 test scores from the eighth grade class
is 31.01. The sample variance of a sample of 21 test scores from
the ninth grade class is 34.54. Test the claim using a 0.005...

A standardized test is given to an eighth grade class and an
eleventh grade class. The superintendent believes that the variance
in performance from the eighth grade class is smaller than the
variance in performance from the eleventh grade class. The sample
variance of a sample of 4 test scores from the eighth grade class
is 22.72. The sample variance of a sample of 14 test scores from
the eleventh grade class is 26.36. Test the claim using a 0.025...

Two teaching methods and their effects on science test scores
are being reviewed. A random sample of 1414 students, taught in
traditional lab sessions, had a mean test score of 77.977.9 with a
standard deviation of 3.33.3. A random sample of 1212 students,
taught using interactive simulation software, had a mean test score
of 85.985.9 with a standard deviation of 55. Do these results
support the claim that the mean science test score is lower for
students taught in traditional...

Two teaching methods and their effects on science test scores
are being reviewed. A random sample of 14 students, taught in
traditional lab sessions, had a mean test score of 72.7 with a
standard deviation of 6. A random sample of 16 students, taught
using interactive simulation software, had a mean test score of
81.6 with a standard deviation of 5.5. Do these results support the
claim that the mean science test score is lower for students taught
in traditional...

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