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Question 45 Not yet answered Points out of 1.00 Flag question To investigate the effect of smoking on breathing, the tidal volumes of 100 people who smoke and 100 non-smokers were measured using spirometry. To see if there was a significant difference in tidal volume measurements between the two groups of people, a t-test was carried out. The t-test results are presented in this table. Which of the following would be the best conclusion best on the t-test results? Variable 2 Mean Variance Obser ons Hypothesized Mean Difference Variable 1 10.75 3.721154 14 15.25 2.951923 14 0 df t Stat P[Test) one-tail Critical one-tail P[Test) two-tail Critical two-tail 25 -2.51799 3.97E-07 1.708141 7.93E-07 2.059539 Select one: a. there is no significant difference in tidal volume between smokers and non-smokers b. there is significant difference in tidal volumes between smokers and non-smokers C. No conclusions can be drawn d. accept the null hypothesis and reject the alternative hypothesis Timod

Answer 1

Here the objective is to test if smoking affects breathing or not. So tidal volumes of 100 smokers and non-smokers are observed. Let the population mean of tidal volumes for smokers and non-smokers be ms and mns respectively.

So here we are to test:

Null hypothesis: ms=mns

Alternative hypothesis:ms is not equal to mns

As this is a two tailed test, so a two tailed t test must be performed. At a 5% level of significance, we reject the null hypothesis if the p-value is less than 0.05. here in the table it is given that p-value= 7.93E-07=7.93*10^(-7) which is very very less than 0.05.

Hence we reject the null hypothesis at 5% level of significance.

Hence there is significant difference in mean tidal volumes between smokers and non-smokers.

Answer: option B is correct.

Hope the solution helps. Thank you.

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