Researchers found the influence of background noise on class performance for children. They found that calming music led to better performance on a math task compared to a no-music condition. A researcher selects one class of n = 18 student who listen to calming music. A second class of n = 18 serves as a control group with no music. The average for student in the first class is M = 86.4 with SS = 1550 compared to an average of M = 78.8 with SS = 1204 for students in the second class. Use α = .05.   a. Is there a significant difference between the two music conditions? b. Compute the 90% confidence interval.

Studies indicate that excessive noise at night can affect weight gain. One study of n = 127 rats compared the weight gain of rats exposed to excessive noise at night and the weight gain of rats in a quiet night environment. Sample statistics for the study are given in the table below. Use this information to determine if there is significant evidence that weight gain of rats exposed to excessive noise at night is different on average than weight gain of rats in a quiet night environment.        Excessive noise at night environment  (Group 1)   Quiet night environment  (Group 2) Sample mean (grams) 22.4 19.9 Sample standard deviation (grams) 6.4 3.8 Observations/Sample size 69 58       The p-value for this test is 0.0086. Make a decision and conclusion for the hypothesis test in context. Use a 5% significance level (α = 0.05).

A researcher wants to test a new memory performance supplement that has shown some promise in primate studies where subjects were given the supplement followed by the task of identifying pictures of other animals three days later. The dependent variable was measured by the number of pictures correctly identified. The researchers noticed that while there was a positive correlation between the group given the supplement and number of correctly identified pictures as compared to the control group, they also notice that there seemed to be some variation between the males and females of the primates. Additionally, two different amounts of the drug have been proposed for consideration. Therefore, in the current study, the researchers want to divide the subject primates (N=60) by gender (male: n=30; female: n=30), and give them a 10 mg dose in one treatment condition, and a 25 mg dose in the other treatment condition. To do this, they are dividing each group of males and females in half, and…

In a One-way Between Subject ANOVA, the number of levels the IV had was 3, and the within/error degrees of freedom was 48. What was the total number of people in the participants analyzed in the study