Assignment:
Answer questions 1 - 3 based on the following information.
Q1: A firm has an order process time of at least 20 minutes. After a change in the process, a researcher wishes to determine if the processing time for orders in a warehouse averages less than 20 minutes, at a 99% confidence level. The researcher uses a sample of 80 orders from a monthly run of 10,000 orders and determines a sample mean of 19 minutes with a standard deviation of 3 minutes.
The null hypothesis is:
Choose one answer.
a. H1 :μ = 20 minutes
b. H0 : μ = 20 minutes
c. H0 : μ>20 minutes
d. H0 : μ <20 minutes
This is an example of a:
Choose one answer.
a. an upper-tailed test.
b. a lower-tailed test.
c. a two-tailed test.
Q2: The decision rule is:
Choose one answer.
a. Fail to reject H0 if z is between -2.58 and +2.58; reject otherwise.
b. Fail to reject H0 if z is between -1.96 and +1.96; reject otherwise.
c. Fail to reject H0 if z is > +2.33; reject otherwise.
d. Fail to reject H0 if z is < -2.33; reject otherwise.
e. Fail to reject H0 if z is > -2.33; reject otherwise.
Q3: The researcher should reject the null hypothesis.
Choose one answer.
a. True
b. False
Q4: Answer questions 4-6 using the following information.
A sample of 60 observations yields a mean of 160 and a sample standard deviation of 40. A sample of 50 observations of another population yields a mean of 149 and a sample standard deviation of 38. A test at the α= 0.05 level of significance is performed for
H0 : µ1≤ µ2 ; H1 : µ1 > µ2 .
This is an example of a(n):
Choose one answer.
a. lower-tailed test.
b. upper-tailed test.
c. two-tailed test.
Q5: The value of the test statistic and p-value are, respectively,:
Choose one answer.
a. 1.48, 0.0694
b. 1.61, 0.027
c. 1.96, 0.035
d. 2.28, 0.537
Q6: The results indicate that the null hypothesis should:
Choose one answer.
a. be rejected.
b. not be rejected.
Q7: Answer questions 7 and 8 using the following information.
A report indicates that readership of a home improvement magazine is split evenly among men and women. A random sample of 600 subscribers identifies that 330 are women. The results are tested at the a= 0.05 level of significance that the report is false.
The null hypothesis and computed value for this problem are, respectively,:
Choose one answer.
a. H0 :μ<0.50; z = 0.46
b. H0 : μ = 0.50; z = 1.96
c. H0 : μ= 0.50; z = 2.45
d. H0 : μ ≠ 300; z = 2.58
Q8: We should conclude that the report is false.
Choose one answer.
a. True.
b. False
Q9: Answer questions 9 and 10 using the following information.
In a sample of its readership, 144 of 300 readers in one income bracket approved of the editorial positions of a newspaper. In a different income bracket, 224 of 400 readers approved of the editorial positions. The newspaper wishes to determine if there is a significant difference between the approval rates at an α= 0.05 level of significance.
The computed value of z is:
Choose one answer.
a. 1.645
b. 1.96
c. 2.02
d. 2.1
e. 55.55
Q10: The test results indicate that there is a significant difference between the approval rates of the separate income brackets.
Choose one answer.
a. True
b. False
Q11: The student t distribution:
Choose one answer.
a. is preferred over the normal distribution for very large size samples.
b. tends to coincide with the normal distribution for large sample sizes.
c. resembles a curve that is heavily skewed to the left.
d. both a and c.
e. none of the above.
Q12: The student t distribution will tend to lead to less Type I errors for small samples.
Choose one answer.
a. True
b. False
Q13: For a lower-tailed test, when the sample mean is 50, the null hypothesis mean is 52.5, s = 7 and n = 25; the student t statistic is:
Choose one answer.
a. 2.091
b. -1.79
c. -2.5
d. 1.63
Q14: For sample A, n = 12 and s2 = 240; for sample B, n = 18 and s2 = 360. The pooled variance of the samples is:
Choose one answer.
a. 20
b. 300
c. 312.86
d. 350.76
e. not calculable without additional data.
Q15: Answer questions 15 and16 based on the following information.
Procedure 1:n = 6; σ= 10; s2 = 8;
Procedure 2:n = 6; σ = 14; s2 = 12;
The number of degrees of freedom for the t statistic is:
Choose one answer.
a. 5
b. 10
c. 11
d. 12
Q16:The pooled variance and t statistic are, respectively :
Choose one answer.
a. 10; -2.19
b. 12; -0.8
c. 12.5; 1.2
d. 15; 1.0