STAT
16 PRACTICE TEST 4
 In a random sample of 600
people in the North, only 160 felt that the president was doing a good
job. Another random sample in the South showed 110 of 500 felt that the president
was doing a good job. Construct a 79% confidence interval for the
difference in true proportions from these groups..
 A Typing teacher wants to
determine whether the mean typing speed of a certain student is different
from 60 wpm. What can she conclude if in 6 one minute intervals the
student typed 70, 69, 39, 87, 68, and 28 wpm. Use
.05 level of significance.
 A sample of Fortyfive Red
Delicious Apples had mean sugar content of 0.4 g/oz with sd=0.04, while another sample of �SixtyTwo Granny Smith had a mean
sugar content of 0.37 g/oz with sd=0.05. �Do the Red Delicious Apples have a higher
sugar then the Granny Smith Apples? �Use .05 �level of significance.
 Page 500 10.80 part a� and�
part b
 The following data shows the
number of months where 0,1,2,3 bank robberies occurred over tens years.
Number of Bank Robberies

Zero

One

Two

Three

Number of months over 10 Years

50

40

20

10

Expected Probability

.5

.3

.1

.1

At a 5% level does the sample fit the theorized expected probabilities?
 The following table gives the
distribution of students according to music they prefer and their IQ.

High

Medium

Low

Classical

5

10

5

Rock

10

10

10

Jazz

10

10

10

Country

5

10

5

At a 5% level, test the null hypothesis that music taste and IQ are
independent attributes.
 Measurements of the growth of
plum trees and the number of days of sunshine for a one month period are
gathered from different farms across the country
Growth

Days of sunshine

7

10

8

11

6

9

9

10

8

10

10

14

7

8

12

15

 Find the leastsquare
line from which we can predict the days of sunshine from growth. Graph the
regression line along with the scatter diagram.
 Find the correlation
coefficient.