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Multiple choice questions

Question 1
Which level of confidence would produce the widest confidence interval?
A. 98%
B. 90%
C. 95%
D. 99%

Question 2
What is the margin of error if c = 0.9, s = 1.5, n = 50
A. 1.645
B. 0.1
C. 0.349
D. 0.049

Question 3
For a sample less than 30 we can use t-distribution only if
A. The population is normally, or approximately normally, distributed.
B. s is unknown
C. s is known
D. Both A & B

Question 4
If level of confidence is 85% then what will be the critical value, zc?
A. 1.645
B. 1.037
C. 1.439
D. 0.85

Question 5
If level of confidence is 85% then what is the value of c?
A. 0.15
B. 0.85
C. 0.075
D. 1

Question 6
What is the critical value tc for confidence level c = 0.95 and sample size n = 10
A. 2.228
B. 2.262
C. 1.812
D. 1.833

Question 7
Which statement is true for a t-distribution?
A. It is a positively skewed curve.
B. It is a single curve determined by the sample size.
C. It is very close to the standard normal distribution when d.f. >= 30.
D. None of the above.

Question 8
What is the critical value of XL
2 for 95% confidence interval when the sample size is
20?
A. 8.907
B. 30.144
C. 32.852
D. 10.117

Question 9
What are the critical values XR
2 and XL
2 for c = 0.99 confidence level and sample size of n = 13
A. 28.299, 3.074
B. 16.919, 3.325
C. 35.479, 10.283
D. 44.314, 11.524

Question 10
You wish to estimate accurately with 95% confidence and within 3% of the true population, the proportions of television sets that need repairs or have problems by the time the product is three years old. If no preliminary estimate is available, what is the minimum sample size required?
A. 1070
B. 1600
C. 1067
D. 1068

Question 11
A statement or claim about a population parameter is called
A. Null Hypothesis
B. Alternative Hypothesis
C. Statistical Hypothesis
D. All of the above

Question 12
Which statement is true for alternative hypothesis?
A. It is the complement of the null hypothesis
B.It must be true if the null hypothesis is false.
C.It is a statistical hypothesis that contains a statement of inequality.
D. All of the above

Question 13
If Ho : M >= 5; Ha : M < 5; then the hypothesis test is a
A. Left-tailed test
B. Right-tailed test
C. Two-tailed test
D. None of the above

Question 14
If a (alpha) = 0.05 then for a right-tailed test the critical value would be?
A. 1.645
B. 1.65
C. 1.28
D. -1.33

Question 15
If a (alpha) = 0.01 then for a left-tailed test the critical value would be?
A. 1.28
B. -2.23
C. -2.33
D. 1.65

Question 16
Find the P-value for a two-tailed test with a test statistic of z = 1.33
A. 1.8164
B. 0.1836
C. 0.0182
D. 0.1188

Question 17
Find the critical value to for a left-tailed test, given that a (alpha) = 0.01 & n = 19
A. 2.539
B. 2.552
C. -2.539
D. -2.552

Question 18
A large university says the mean number of class room hours per week for full time faculty is more than 9. So the null & alterative hypothesis are:
A. Ho : M = 9; Ha : M not equal to 9
B. Ho : M < 9; Ha : M >= 9
C. Ho : M <= 9; Ha : M > 9
D. Ho : M > 9; Ha : M <= 9

Question 19
A medical researcher estimates that no more than 55% of US adults eat breakfast everyday. In a random sample of 250 US adults, 61% say that they eat breakfast everyday. At a (alpha) = 0.05, which decision is appropriate for this problem?
A. Fail to reject null hypothesis
B. Reject null hypothesis
C. None of the above
D. Both A & B

Question 20
What is the critical X values for a two-tailed test when n = 11 & a (alpha) = 0.01
A. 2.603, 26.757
B. 2.156, 25.188
C. 2.558, 23.209
D. 3.053, 24.725

Solution Preview

Question 1
Which level of confidence would produce the widest confidence interval?
A. 98%
B. 90%
C. 95%
D. 99%
The more the level of confidence required, the wider is the confidence interval

Question 2
What is the margin of error if c = 0.9, s = 1.5, n = 50
A. 1.645
B. 0.1
C. 0.349
D. 0.049
Z value for 90% confidence = 1.6449
Standard error = s/ square root of n = 1.5 / square root of 50 = 0.2121
1.6449 x 0.2121= 0.349

Question 3
For a sample less than 30 we can use t-distribution only if
A. The population is normally, or approximately normally, distributed.
B. s is unknown
C. s is known
D. Both A & B
Answer: D. Both A & B

Question 4
If level of confidence is 85% then what will be the critical value, zc?
A. 1.645
B. 1.037
C. 1.439
D. 0.85
(we are assuming it is 2 tailed test)
Confidence level= 85%
or Significance level a (alpha) = 0.15
No of tails= 2
Z value corresponding to 0.15 significance level and 2 tails= 1.4395
(For 1 tailed test it would be 1.037)
Confidence level= 85%
or Significance level a (alpha) = 0.15
No of tails= 1
Z value corresponding to 0.15 significance level and 1 tails= 1.0364

Question 5
If level of confidence is 85% then what is the value of c?
A. 0.15
B. 0.85
C. 0.075
D. 1

Question 6
What is the critical value tc for confidence level c = 0.95 and sample size n = 10
A. 2.228
B. 2.262
C. 1.812
D. 1.833
(we are assuming it is 2 tailed test)
Confidence level= 95%
Or Significance level a (alpha) = 0.05
n= 10
degrees of freedom=n-1= 9 =10- 1
No of tails= 2
t value= 2.2622 (corresponding to 9 degrees of freedom and 0.05 significance level )
(For 1 tailed test it would be 1.833)
Confidence level= 95%
Or Significance level a (alpha) = 0.05
n= 10
degrees of freedom=n-1= 9 =10- 1
No of tails= 1
t value= 1.8331 (corresponding to 9 degrees of freedom and 0.05 significance level )

Question 7
Which statement is true for a t-distribution?
A. It is a positively skewed curve.
B. It is a single curve determined by the sample size.
C. It is very close to the standard normal distribution when d.f. >= 30.
D. None of the above.