A Tutor Promises to Improve GMAT Scores of Students by More

question 21

Multiple Choice

A tutor promises to improve GMAT scores of students by more than 50 points after three lessons. To see if this is true, the tutor takes a sample of 49 students' test scores after and before they received tutoring. The mean difference was 53 points better after tutoring, with a standard deviation of the difference equal to 12 points. Let µ_D denote the mean of the difference: score after tutoring minus score before tutoring. Assuming α = 0.05, which of the following is the appropriate critical value?

• A) z = 1.677
• B) z = 2.011
• C) t_0.05,48 = 1.677
• D) t_0.05,₄₈ = 2.011

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Definitions:

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Specific geometrical forms designed for connecting pipes, valves, pumps, and other equipment to form a piping system.

Miscellaneous Channels

Various minor or diverse types of channel-shaped structural elements.

Weight Pounds

A measurement of weight using the pound as the unit, commonly used in the English measurement system.

Rolling Mill

A machine or factory setup for rolling metal into sheets, rods, or various shapes through compressive forces applied by rotating rolls.