The mean crying time of infants during naptime at a local preschool is 12 min.The school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8±4.6 (M±SD)min.Test whether this new naptime routine reduced crying time at a .05 level of significance. A) The new naptime routine significantly reduced crying time, t(24) = -4.35, p

Question

The mean crying time of infants during naptime at a local preschool is 12 min.The school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8±4.6 (M±SD)min.Test whether this new naptime routine reduced crying time at a .05 level of significance.
A) The new naptime routine significantly reduced crying time, t(24) = -4.35, p < .05.
B) The new naptime routine did not reduce crying time, t(24) = -4.35, p < .05.
C) The new naptime routine did not reduce crying time, t(24) = 8.67, p > .05.
D) The new naptime routine significantly reduced crying time, t(24) = 8.67, p < .05.

Quizplus · Accepted Answer

To test whether the new naptime routine reduced crying time, we need to conduct a one-sample t-test. The null hypothesis would be that the mean crying time of infants during naptime with the new routine is not significantly different from the mean crying time of infants during naptime at the local preschool, which is 12 min. The alternative hypothesis would be that the mean crying time is significantly less than 12 min with the new routine.
 
In this case, the sample mean is 8 min, which is 4 units of SD below the population mean. We can calculate the t-value as follows: t = (8 - 12) / (4.6 / sqrt(25)) = -4.35. Degrees of freedom for this test is (25-1) = 24.

Using a t-table or statistical software, we can find that the p-value for this test is less than .05 (p < .05). Therefore, we reject the null hypothesis and conclude that the new naptime routine significantly reduced crying time. The correct answer is A.

The Mean Crying Time of Infants During Naptime at a Local