Question

SAT scores: The College Board reports that in 2009, the mean score on the math SAT was 582 and the population standard deviation was =σ120. A random sample of 20 students who took the test in 2010 had a mean score of 515. Following is a dotplot of the 20 scores. (a) Are the assumptions for a hypothesis test satisfied? Explain. (b) If appropriate, perform a hypothesis test to investigate whether the mean score in 2010 differs from the mean score in 2009. Assume the population standard deviation is =σ120. What can you conclude? Use the =α0.10 level of significance and the critical value method.

Answer 1

we can conclude that there is no significant evidence to conclude that the mean score in 2010 differs from the mean score in 2009.

Explanation:

H0 : μ = 582

H1 : μ < 582

Test statistic :

T = (xbar - μ) ÷ σ/√n

Xbar = 515 ; n = 20 ; σ = 120

T = (515 - 582) ÷ 120/√20

T = -67 / 26.832815

T = 2.50

Pvalue at t score = 2.50 ; df = 19 is 0.0187

At α = 0.0187

Pvalue > α ; Hence, we fail to reject the Null

Hence, we can conclude that there is no significant evidence to conclude that the mean score in 2010 differs from the mean score in 2009.