A company that sells an online course aimed at helping high-school students improve their SAT scores has claimed that SAT scores will improve by more than 90 points on average if students successfully complete the course.
To test this, a national school counseling organization plans to select a random sample of n = 100 students who have previously taken the SAT test. These students will take the company's course and then retake the SAT test. Assuming that the population standard deviation for improvement in test scores is thought to be 30 points and the level of significance for the hypothesis test is 0.05, what is the probability that the counseling organization will incorrectly accept the null hypothesis when, in fact, the true mean increase is actually 95 points?A) Approximately 0.508
B) About 0.492
C) Approximately 0.008
D) Can't be determined without knowing the sample results.
Question 2
In conjunction with the housing foreclosure crisis of 2009, many economists expressed increasing concern about the level of credit card debt and efforts of banks to raise interest rates on these cards. The banks claimed the increases were justified.
A Senate subcommittee decided to determine if the average credit card balance depends on the type of credit card used. Under consideration are Visa, MasterCard, Discover, and American Express. The sample sizes to be used for each level are 25, 25, 26, and 23, respectively.State the number of degrees of freedom available for determining the between-samples variation.A) 6
B) 5
C) 2
D) 3
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