Question

After the 8-week program, those who participated in the aquarobic program had their ending cholesterol measured, and the change in cholesterol was recorded for each participant. Estimate the mean cholesterol change using 90% confidence.

1) The formula which should be used for this interval is:

2) With __ % confidence, we estimate that the mean cholesterol before participating in 8 weeks of aquarobics is between __ mg and __ mg than the mean cholesterol after participation. Note: Round the limits of your interval to three decimal places. In the last box type the appropriate word - moreor less. Think carefully about what positive and negative differences mean about the change in cholesterol based on how the differences were taken.

Difference	Sample Diff.	Std. Error	Critical Pt
Pre - Post	17.1167	0.8569	1.6909

3) A 90% confidence interval was also calculated for the change in total cholesterol (pre - post) for the control group. That interval was found to be (-0.83, 2.902). Based on this interval and the one which you calculated for the aquarobic group, what conclusion would you draw?

Both groups had a significant decrease in mean cholesterol. However, the decrease for the aquarobic group was larger.

(a)The mean cholesterol for the control group increased, while the aquarobic group had a significant decrease in mean cholesterol.

(b)Neither group had a significant change in mean cholesterol.

(c)The aquarobic group did not have a significant change in mean cholesterol, while the control group had a significant increase in mean cholesterol.

(d)The control group did not have a significant change in mean cholesterol, while the aquarobic group had a significant decrease in mean cholesterol.

Answer 1

1)
formula
=(xbar - t * sd/sqrt(n) , xbar+ t * sd/sqrt(n))
standard error = sd/sqrt(n)

2)
90 % confidence interval
(17.1167 - 1.6909 * 0.8569 , 17.1167 + 1.6909 * 0.8569)
= (15.6677 , 18.56563221)
=(16.668,18.566)

3)
since 0 is present in confidence interval , we fail to reject the null hypothesis

hence
option (d)The control group did not have a significant change in mean cholesterol, while the aquarobic group had a significant decrease in mean cholesterol.
is correct

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