# Help The basic practive of statisitc 4th edition

#### 1happyday

##### New Member
Hello,

I am looking for answers for the sample problems so that I can have a better understanding of Confidence Intervals and Signigicance Tests) Does anyone have this edtion or know were I can locate the solutions to the problems?

19.42 Coaching and SAT Scores.
Coaching companies claim that their cources can raise the SAT scores of high school students. Of Course, Students who retake the SAT without paying for coaching generally raise their scores. A random sample of studente who took the SAT twice found 427 who were coached and 2733 who were uncoached. Starting with their verables scores on the first and second tries, we have these summary Statistics:

Try 1 Try 2 Try 3
x s x s x s
Coached 500 92 529 97 29 59
Uncoached 506 101 527 101 21 52

Let's first ask if students who are coached signigicantly increase theit scores.
a) You could use the information given to carry out either a two-sample t test comparing Try 1 with Try 2 for coached students or a matched pairs t test using Gain. Which is the correct test? Why?

b) Carry out the proper test. What do you conclude?

C) Given a 99% confidence interval for the mean gain of all students who are coached.