C. There isn't much evidence to support a conclusion that the presence of carpet is associated with an increase or decrease in the mean bacterial concentration of air is correct answer.
The P-value for this test is greater than 0.25. So, we can't reject the null hypothesis, which is that there is no difference in the mean bacterial concentration of air between carpeted and uncarpeted rooms.
Therefore, the most reasonable conclusion is that there isn't much evidence to support a conclusion that the presence of carpet is associated with an increase or decrease in the mean bacterial concentration of air.
So the answer is C.
Question
Is there a difference in the amount of airborne bacteria between carpeted and uncarpeted rooms? In an experiment, seven rooms were carpeted and seven were left uncarpeted. The rooms are similar in size and function. After a suitable period, the concentration of bacteria in the air was measured (in units of bacteria per cubic foot) in all of these rooms. The P-value for this test is greater than 0.25. Which of the following is a reasonable conclusion?A. There are outliers in these data, so we can't rely on the two-sample t test.B. This test is unreliable because the populations we're sampling from are heavily skewed.C. There isn't much evidence to support a conclusion that the presence of carpet is associated with an increase or decrease in the mean bacterial concentration of air.D. There is fairly strong evidence to support a conclusion that the presence of carpet is associated with an increase or decrease in the mean bacterial concentration of air.