Exhibit 8-3
1.A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph.
Refer to Exhibit 8-3. The 86.9% confidence interval for μ is _____.
57.735 to 62.265
2.A random sample of 16 students selected from the student body of a large university had an average age of 23 years. We want to determine if the average age of all the students at the university is significantly different from 21. Assume the distribution of the population of ages is normal with a standard deviation of 4 years.
At a 0.05 level of significance, it can be concluded that the mean age is _____.
significantly different from 21
3.The probability distribution of all possible values of the sample mean is called the ____.
sampling distribution of the sample mean
Exhibit 3-2
4.A researcher has collected the following sample data. The mean of the sample is 5.
3 | 5 | 12 | 3 | 2 |
10
5.Random samples of size 100 are taken from a process (an infinite population) whose population proportion is .2. The mean and standard deviation of the distribution of sample proportions are _____.
2 and .04
6.The probability Pete will catch fish when he goes fishing is 0.6. Pete is going fishing 4 days next week.
The probability that Pete will catch fish on 1 or fewer days is _____.
0.179
7.Excel’s _____ function can be used to compute the sample correlation coefficient.
CORREL
8.The numbers of hours worked (per week) by 390 statistics students are shown below.
| Number of Hours | Frequency | |||
| 0 ≤ x < 20 | 20 | |||
| 20 ≤ x < 40 | 100 | |||
| 40 ≤ x < 60 | 180 | |||
| 60 ≤ x < 80 | 90 | |||
70
9.An auto manufacturer wants to estimate the annual income of owners of a particular model of automobile. A random sample of 200 current owners is selected. The population standard deviation is known. Which Excel function would NOT be appropriate to use to construct a confidence interval estimate?
COUNTIF
Exhibit 5-4
10.A local bottling company has determined the number of machine breakdowns per month and their respective probabilities as shown below.
| Number of | |
| Breakdowns | Probability |
| 0 | .12 |
| 1 | .38 |
| 2 | .25 |
| 3 | .18 |
| 4 | .07 |
1.70
11.If the margin of error in an interval estimate of μ is 4.8, the interval estimate equals _____.
x̄ ± 4.8
12.If P(A) = 0.74, P(A ∪ B) = 0.82, and P(A ∩ B) = 0.58, then P(B) = _____.
0.66
13.If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be _____.
.1
13.Categorical data _____.
may be either numeric or nonnumeric
14.An experiment consists of tossing four coins successively. The number of sample points in this experiment is 16, What is the difference between a bar graph and a histogram?
A histogram displays quantitative data, while a bar graph displays categorical data.
15.If P(A) = 0.67, P(B) = 0.59, and P(A ∪ B) = 0.80, then P(B | A) = _____.
0.6866
Exhibit 2-3
16.The number of sick days taken (per month) by 200 factory workers is summarized below.
| Number of Days | Frequency | |||
| 0 − 5 | 120 | |||
| 6 − 10 | 65 | |||
| 11 − 15 | 14 | |||
| 16 − 20 | 1 | |||
15
Exhibit 5-5
17.AMR is a computer-consulting firm. The number of new clients that it has obtained each month has ranged from 0 to 6. The number of new clients has the probability distribution that is shown below.
| Number of | |
| New Clients | Probability |
| 0 | .05 |
| 1 | .10 |
| 2 | .15 |
| 3 | .35 |
| 4 | .20 |
| 5 | .10 |
| 6 | .05 |
1.431
18.For a standard normal distribution, the probability of obtaining a z value between –2.4 and –2.0 is _____.
0146
19.A random sample of 144 bottles of cologne showed an average content of 5 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.48 ounces.
The point estimate of the mean content of all bottles is _____.
5 ounces
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