Answer:
We conclude that the blood pressure has decreased or remained same because of speaking.
Step-by-step explanation:
We are given that a class of 15 statistics students participated in the study.
The resulting values are given below along with summary statistics;
Before 102 123 128 125 136 108 130 113 105 136 146 138 108 149 132
After 141 142 146 136 144 111 132 114 103 133 140 130 100 133 113
Before-After -39 -19 -18 -11 -8 -3 -2 -1 2 3 6 8 8 16 19
Before After Difference
Mean = 125.3 Mean = 127.9 Mean = -2.6
StDev = 15.03 StDev = 15.5 StDev = 14.87
Let = mean blood pressure of students after speaking.
= mean blood pressure of students before speaking.
= = difference between two mean blood pressures.
So, Null Hypothesis, : 0 or 0 {means that the blood pressure has decreased or remained same because of speaking}
Alternate Hypothesis, : < 0 or < 0 {means that the blood pressure has increased because of speaking}
The test statistics that would be used here <u>Paired data t-test statistics</u>;
T.S. = ~
where, = sample mean difference in both blood pressure = -2.6
= sample standard deviation of paired data = 14.87
n = sample of statistics students participated = 15
So, <u><em>the test statistics</em></u> = ~
= -0.677
The value of t test statistics is -0.677.
<u>Now, at 0.05 significance level the t table gives critical value of -1.761 at 14 degree of freedom for left-tailed test.</u>
Since our test statistic is more than the critical value of t as -0.677 > -1.761, so we have insufficient evidence to reject our null hypothesis as it will not fall in the rejection region due to which <u>we fail to reject our null hypothesis</u>.
Therefore, we conclude that the blood pressure has decreased or remained same because of speaking.