Question

Dr. Smith was interested in examining if weekly exercise would produce a change in the stress levels among individuals in the population. In general population of college students, scores on a standardized stress test that are normally distributed with the mean µ = 20 and standard deviation σ = 5. Because it was not feasible to ask everyone in the population to exercise weekly, a sample of n = 16 individuals was selected, and the exercise training program was given to this sample. After exercising, the average stress score for this sample was ?̅ = 17. Can the researcher conclude that exercise would have an effect on stress levels? Round up to two decimal places. Use a two-tailed test and α = .05.

Q1: State your null hypothesis and research hypothesis in complete sentences.

Q2: what are the cut-off points?

Q3: What is the standard error?

Q4: What is the z-score?

Q5: Write your conclusion thoroughly.

Answer #1

1)

H0: = 20 ,

Ha: 20

2)

z critical values at 0.05 significance level = **-1.96 ,
1.96**

3)

Standard error =
/ sqrt ( n) = 5 / sqrt(16) = **1.25**

4)

z-score = ( - ) / SE

= ( 17 - 20) / 1.25

= **-2.4**

5)

Since test statistics > 1.96 reject H0.

We have sufficient evidence to conclude that exercise would have an effect on stress levels.

For your answers pick one
*A researcher was interested in inspecting the effect of
classical music on stress among New York students. She studied a
sample of 30 New York students. She found that z= -3.00. Using a =
0.5(two-tailed), what can she conclude?
-Reject the null hypothesis and conclude that classical music
has no effect on stress levels
-Reject the null hypothesis and conclude that classical music has
no effect on stress levels
-Failed to reject the null hypothesis...

BIOS 376 Homework 7
1. A professor claims that the mean IQ for college students is
92. He collects a random sample of 85 college students to test this
claim and the mean IQ from the sample is 84.
(a) What are the null and alternative hypotheses to test the
initial claim? (1 pt)
(b) Using R, compute the test statistic. Assume the population
standard deviation of IQ scores for college students is 17.6
points. (1 pt)
(c) Using R,...

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