You Are Evaluating Investing in a Cognitive Training Company

question 94

Multiple Choice

You are evaluating investing in a cognitive training company.For this reason,you want to determine whether users who complete at least 75% of the recommended daily training for two months show improved levels of reading comprehension and problem solving skills.You select a random sample of new users and get test scores for each participant in the sample.The test score is a composite of reading comprehension and problem solving skills.Two months later,you randomly select 15 users who have completed 75% or more of the recommended training for the last two months and have them take a test similar to the initial test.You are interested in determining whether the average test score before training is different than the average test score after training for this sample.The after-training average is 92.8,which is 2.7 points higher than the before-training average.The sample standard deviations of the differences is 1.2.You can assume that the differences are normally distributed in the population.The degrees of freedom for this test are ______.

• A) 30
• B) 29
• C) 28
• D) 15
• E) 14

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Definitions:

NAACP

The National Association for the Advancement of Colored People, a civil rights organization founded in 1909 to fight prejudice, lynching, and Jim Crow segregation.

Bull Moose

Refers to the Progressive Party of 1912 in the United States, symbolized by a bull moose, led by Theodore Roosevelt after a split in the Republican Party.

Progressive Republicans

A faction within the Republican Party in the early 20th century that advocated for reforms including anti-corruption measures, environmental conservation, and worker's rights.

African-American

A term referring to citizens or residents of the United States who have total or partial ancestry from any of the black racial groups of Africa.