1) A nurse at a local hospital is interested in estimating the birth weight of infants. How large
a sample must she select if she desire to be 95% confident that the true mean is within 3
ounces of the sample mean? The standard deviation of the birth weights is known to be 9
ounces.
a)34 b)6 c)35 d)5
,
,
The minimum sample size is 35.
2) Determine the standardized test statistic, z, to test the claim about the population p does
not equal 0.325 given n=42 and p-hat=0.247. Use a= 0.05.
a) -1.08 b)-1.54 c) -2.575 d)-1.32
3) Two surgical procedures are widely used to treat a certain type of cancer. To compare the
success rates of the two procedures, random samples of the two types of surgical patients
were obtained and the numbers of patients who showed no recurrence of the disease after a 1year period were recorded. The data are shown in the table.
n
Number of Successes
PROCEDURE A 100
93
PROCEDURE B 100
96
How large a sample would be necessary in order to estimate the difference in the true success
rates to within .10 with 95% reliability.
a) n1=n2 =28 b) n1=n2=20 c) n1=n2=40 d) n1=n2=192
The minimum sample size is
4) Find the critical t-value that corresponds to c= 0.95 and n=16.
a) 2.131 b) 2.947 c) 2.602 d) 1.753
Using tables of t distribution, 5% two sided critical value of t for 16-1=15 degrees of freedom
=2.131