practice set 4 for my QNT275
. Find z for each of the following confidence levels. Round to two decimal places.
A. 90%
B. 95%
C. 96%
D. 97%
E. 98%
F. 99%
2. For a data set obtained from a random sample, n = 81 and x = 48.25. It is known
that ? = 4.8.
A. What is the point estimate of ?? Round to two decimal places
B. Make a 95% confidence interval for ?. What is the lower limit? Round to two decimal places.
C. Make a 95% confidence interval for ?. What is the upper limit? Round to two decimal places.
D. What is the margin of error of estimate for part b? Round to two decimal places.
3. Determine the sample size (nfor the estimate of ? for the following.
A. E = 2.3, ? = 15.40, confidence level = 99%. Round to the nearest whole number.
B. E = 4.1, ? = 23.45, confidence level = 95%. Round to the nearest whole number.
C. E = 25.9, ? = 122.25, confidence level = 90%. Round to the nearest whole number.
4. True or False.
a.The null hypothesis is a claim about a population parameter that is assumed to be false until it is declared false.
A. True
B. False
b. An alternative hypothesis is a claim about a population parameter that will be true if the null hypothesis is false.
A. True
B. False
c. The critical point(s) divide(s) is some of the area under a distribution curve into rejection and nonrejection regions.
A. True
B. False
d. The significance level, denoted by ?, is the probability of making a Type II error, that is, the probability of rejecting the null hypothesis when it is actually true.
A. True
B. False
e. The nonrejection region is the area to the right or left of the critical point where the null hypothesis is not rejected.
A. True
B. False
What is the value of z? Round to two decimal places.
Would you reject the null hypothesis?
Reject Ho
Do not reject Ho
7. The following information is obtained from two independent samples selected from two normally distributed populations.
n1 = 18 x1 = 7.82 ?1 = 2.35
n2 =15 x2 =5.99 ?2 =3.17
A. What is the point estimate of ?1 ? ?2? Round to two decimal places.
B. Construct a 99% confidence interval for ?1 ? ?2. Find the margin of error for this estimate.
Round to two decimal places.
8. The following information is obtained from two independent samples selected from two
populations.
n1 =650 x1 =1.05 ?1 =5.22
n2 =675 x2 =1.54 ?2 =6.80
Test at a 5% significance level if ?1 is less than ?2.
a) Identify the appropriate distribution to use.
t distribution
normal distribution
b) What is the conclusion about the hypothesis?
A. Reject Ho
B. Do not reject Ho
