CALIFORNIA STATE UNIVERSITY, HAYWARD
STATISTICS DEPARTMENT


Statistics 1000 Elements of Probability and Statistics


MINI-PROJECT 4

Confidence Intervals

 

  1. z Confidence Interval for .  Consider problem 31, page 261:  A publisher wants to estimate the mean length of time adults spend reading newspapers.  To do this, the publisher takes a random sample of 15 people and gets the following results.

 

11, 9, 8, 10, 10, 9, 7, 11, 11, 7, 6, 9, 10, 8, 10

               

                From past studies, the publisher assumes  is 1.5 minutes.  Enter the numbers in C1.

    1. Construct a 95% z confidence interval for .

Stat > Basic Statistics > 1-Sample z > C1 > Sigma: 1.5 > OK

 

  1. t Confidence Interval for .  Consider problem 19, page 272:  The SAT score of 12 randomly selected senior high school students are

 

1424, 1223, 987, 692, 947, 723, 837, 721, 747, 540, 623, 1445

 

Enter the numbers into C2.

    1. Calculate the sample mean and sample standard deviation. 

Stat > Basic Statistics > Descriptive Statistics > C1 > OK

    1. Construct a 95% t confidence interval for . 

Stat > Basic Statistics > 1-Sample t > C2 > OK

 

  1. Confidence Interval for p.  Consider the following problem:  Suppose a class poll is taken to determine the proportion of people who like Roy Orbison’s music.  Of the 20 people polled 5 say they like his music.  The following data uses 1 = YES and 0 =NO.

 

1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0

 

        Enter the numbers into C3.

    1. Calculate a 95% confidence interval for p.

Stat > Basic Statistics > 1 Proportion > C3 > OK