PLEASE USE 2 DECIMAL PLACES THROUGHOUT.

1.Methylphenidate is a drug that is widely used in the treatment of attention-deficit disorder.As part of a study, twenty children between the ages of 7 and 12 who suffered from this disorder were randomly assigned to either take the drug (n = 10) or take a placebo (n = 10).Measures of each child's attention and behavioral status were obtained using an instrument called the Parent Rating Scale, for which lower scores indicate greater attention.Distributions of these scores are approximately normal for both the drug treatment and control groups.

The children enrolled in the study had a mean attention rating score= 10.9 and s = 2.8 when taking methylphenidate and mean rating score= 14.1 and s = 3.1 when taking the placebo.

a. What is the standard error for each group?

b. How many degrees of freedom are there for each group? (1pts)

c. What is the associated t-value corresponding to a 95% confidence interval?For a 99% confidence interval?

d. Construct 95% and 99% confidence intervals for the mean attention rating score for children taking the drug. Please answer in the form (lowerbound, upperbound).

e. Construct 95% and 99% confidence intervals for the mean attention rating score for children taking the placebo.

f. Assume the study was actually done with a sample size of 101 children in each group (total = 202 children).What is the new t-value corresponding to a 95% confidence interval?

Also, recalculate the 95% confidence intervals for both the treatment and control groups (use the same mean and standard deviation, but recalculate SE).

g. How do sample size (n) and alpha () affect the confidence interval? Circle all that apply:

1. Increasing widens the interval

2. Increasing narrows the interval

3. Increasing n widens the interval

4. Increasing n narrows the interval