Writing scores for the population having standard deviation

Reference no: EM1395923

State College is evaluating a new English composition course for freshmen. A random sample of n = 25 freshmen is obtained and the students are placed in the course during their first semester. One year later, a writing sample is obtained for each student and the writing samples are graded using a standardized evaluation technique. The average score for the sample is M = 76. For the general population of college students, writing scores form a normal distribution with a mean of µ = 70.

a. If the writing scores for the population have a standard deviation of σ = 20, does the sample provide enough evidence to conclude that the new composition course has a significant effect?

b. If the population standard deviation is σ = 10, is the sample sufficient to demonstrate a significant effect? Again, assume a two-tailed test with α = .05.

c. Briefly explain why you reached different conclusions for part (a) and part (b).

Reference no: EM1395923

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