QUESTION 27 Reducing Errors in Grammar A composition teacher wishes to see wheth

Question

QUESTION 27 Reducing Errors in Grammar A composition teacher wishes to see whether a new grammar program will reduce the number of grammatical errors her students make when writing a two-page essay The data are shown here. At a 0.025 level of significance, can ià be concluded that the number of errors has been reduced? Student Errors before Errors after 12 90 5 43 What is the lower bound? Round to 3 decimal places QUESTION 28 Reducing Errors in Grammar A composition teacher wishes to see whether a new grammar program will reduce the number of grammatical errors her students make when writing a two-page essay. The data are shown here. At a 0 025 level of can it be concluded that the number of errors has been reduced? Student Errors before Errors after What is the upper bound? Round to 3 decimal places 12 9 05 4 3

Explanation / Answer

The statistical software output for this problem is:

Paired T confidence interval:
?D = ?1 - ?2 : Mean of the difference between Errors Before and Errors After
97.5% confidence interval results:

Hence,

Answer - 27: Lower bound = -0.622

Answer - 28: Upper bound = 3.622

Difference Mean Std. Err. DF L. Limit U. Limit Errors Before - Errors After 1.5 0.67082039 5 -0.62206075 3.6220608

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