In an effort to counteract student cheating, the professor of a large class created four versions of a midterm exam, distributing the four versions among the 340 students in the class, so that each version was given to 85 students. After the exam, the professor computed the following information about the scores (the exam was worth 200 points): Sample Sample Sample size Group mean variance Version A 85 159.9 324.1 Version B 85 153.7 449.5 Version C 85 155.4 386.7 Version D 85 153.1 337.1 Send data to calculator Send data to Excel The professor is willing to assume that the populations of scores from which the above samples were drawn are approximately normally distributed and that each has the same mean and the same variance. Answer the following, carrying your intermediate computations to at least three decimal places and rounding your responses to at least one decimal place. (a) Give an estimate of this common population variance by pooling the sample variances given. (b) Give an estimate of this common population variance based on the variance of the sample means given. ?

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In an effort to counteract student cheating, the professor of a large class created four versions of a midterm exam, distributing the four versions among the 340
students in the class, so that each version was given to 85 students. After the exam, the professor computed the following information about the scores (the
exam was worth 200 points):
Sample Sample Sample
size
Group
mean
variance
Version A
85
159.9
324.1
Version B
85
153.7
449.5
Version C
85
155.4
386.7
Version D
85
153.1
337.1
Send data to calculator
Send data to Excel
The professor is willing to assume that the populations of scores from which the above samples were drawn are approximately normally distributed and that
each has the same mean and the same variance.
Answer the following, carrying your intermediate computations to at least three decimal places and rounding your responses to at least one decimal place.
(a) Give an estimate of this common population variance by
pooling the sample variances given.
(b) Give an estimate of this common population variance based
on the variance of the sample means given.
Transcribed Image Text:In an effort to counteract student cheating, the professor of a large class created four versions of a midterm exam, distributing the four versions among the 340 students in the class, so that each version was given to 85 students. After the exam, the professor computed the following information about the scores (the exam was worth 200 points): Sample Sample Sample size Group mean variance Version A 85 159.9 324.1 Version B 85 153.7 449.5 Version C 85 155.4 386.7 Version D 85 153.1 337.1 Send data to calculator Send data to Excel The professor is willing to assume that the populations of scores from which the above samples were drawn are approximately normally distributed and that each has the same mean and the same variance. Answer the following, carrying your intermediate computations to at least three decimal places and rounding your responses to at least one decimal place. (a) Give an estimate of this common population variance by pooling the sample variances given. (b) Give an estimate of this common population variance based on the variance of the sample means given.
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