Men arrive at a service centre according to a Poisson at an average of 6 per hour,
women arrive at a service centre according to a Poisson at an average of 12 per hour,
and children arrive at a service centre according to a Poisson at an average of 12 per
hour. If the centre opens at 9.00 a.m., determine the probability that Andy is the first
customer arriving at the centre after 9.10 a.m. (5%)
0.0067
0.0025
0.3979
0.0076
A municipal bond service has three rating categories (A,B, and C). Suppose that in the
past year, of the municipal bonds issued throughout the US, 70% were rated A, 20%
were rated B, and 10% were rated C. Of the municipal bonds rated A, 50% were issued
by cities, 40% were issued by suburbs, and 10% by rural areas. Of the municipal bonds
rated B, 60% were issued by cities, 20% were issued by suburbs, and 20% by rural areas.
Of the municipal bonds rated C, 90% were issued by cities, 5% were issued by suburbs,
and 5% by rural areas. If a new municipal bond is to be issued by a city, what is the
probability that it will receive an A rating? (5%)
0.525
0.475
0.625
0.375
According to the question above, how many extra observations we should select if we
require the value of a to be 0.21? (5%)
72
73
74
76
F(v1-k , v2-n)
F(v1-n , v2-k)
F(v1-k-1 , v2-n-1)
F(v1-n-1 , v2-k-1)
Testing
A hardware manufacturer produce bolts of 10 mm diameter in factory A. Suppose that an
acceptable standard deviation for the bolt diameters is less than 0.09 mm. The manufacturer
wants to decide whether the diameters of the bolts produced in factory A vary too much by
performing a hypothesis test. The manufacturer takes a random sample of 12 bolts and
derived a sample standard deviation of 0.047mm. Answer question 8 to question 10.
The null and alternative hypothesis for the intended test will be: (5%)
H0 : σ =0.09; H1 : σ ≠0.09
H0 : σ ≥0.09; H1 : σ <0.09
H0 : σ ≤0.09; H1 : σ >0.09
H0 : σ ≤0.047; H1 : σ >0.047
Testing
A hardware manufacturer produce bolts of 10 mm diameter in factory A. Suppose that an
acceptable standard deviation for the bolt diameters is less than 0.09 mm. The manufacturer
wants to decide whether the diameters of the bolts produced in factory A vary too much by
performing a hypothesis test. The manufacturer takes a random sample of 12 bolts and
derived a sample standard deviation of 0.047mm. Answer question 8 to question 10.
The value for the testing statistics is around: (5%)
1
2
3
4
Testing
A hardware manufacturer produce bolts of 10 mm diameter in factory A. Suppose that an
acceptable standard deviation for the bolt diameters is less than 0.09 mm. The manufacturer
wants to decide whether the diameters of the bolts produced in factory A vary too much by
performing a hypothesis test. The manufacturer takes a random sample of 12 bolts and
derived a sample standard deviation of 0.047mm. Answer question 8 to question 10.
The manufacturer draws another random independent sample of size 10 from factory B
and finds the standard deviation about 0.055mm. The manufacturer tries to evaluate
whether the two standard deviations for bolts produced in factory A and B are equal.
The value for the testing statistics and corresponding distribution should be: (5%)
0.73;F9,11
0.73;F11,9
Fill out the blanks (1) ~ (12) in this ANOVA tables. (5%)
Whether is there difference in the means of the monthly sales of the two age groups
or not? (5%) (Hint: Please state the hypotheses, find the critical value and get the
test value, make your decision and summarize the results.)
Whether is there difference in the means of the monthly sales of the three product
groups or not? (5%)
Whether is there interaction effect between the ages of the sales people and the
products they sell on the monthly sales or not? (5%)
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