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:

Hypothalamus

A small but crucial part of the brain located below the thalamus, responsible for controlling hunger, thirst, emotions, body temperature, and circadian rhythms.

Occipital Lobe

The region of the brain located at the back of the head, which is primarily responsible for visual processing.

Primary Visual Cortex

The part of the cerebral cortex responsible for processing visual information, located in the occipital lobe.

Limbic System

A complex system of nerves and networks in the brain, involved with instinct and mood. It controls the basic emotions (fear, pleasure, anger) and drives (hunger, sex, dominance, care of offspring).