1. A numerical description of the outcome of an experiment is called a a. descri
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Question
1. A numerical description of the outcome of an experiment is called a
a.
descriptive statistic
b.
probability function
c.
variance
d.
random variable
2. A random variable that can assume only a finite number of values is referred to as a(n)
a.
infinite sequence
b.
finite sequence
c.
discrete random variable
d.
discrete probability function
3. A continuous random variable may assume
a.
any value in an interval or collection of intervals
b.
only integer values in an interval or collection of intervals
c.
only fractional values in an interval or collection of intervals
d.
only the positive integer values in an interval
4. An experiment consists of making 80 telephone calls in order to sell a particular insurance policy. The random variable in this experiment is the number of sales made. This random variable is a
a.
discrete random variable
b.
continuous random variable
c.
complex random variable
d.
None of the answers is correct.
5. Which of the following is(are) required condition(s) for a discrete probability function?
a.
åf(x) = 0
b.
f(x) ³ 1 for all values of x
c.
f(x) < 0
d.
None of the answers is correct.
6. x is a random variable with the probability function: f(x) =x/6 for x= 1,2 or 3. The expected value of x is
a.
0.333
b.
0.500
c.
2.000
d.
2.333
7. The number of electrical outages in a city varies from day to day. Assume that the number of electrical outages (x) in the city has the following probability distribution.
x
f(x)
0
0.80
1
0.15
2
0.04
3
0.01
The mean and the standard deviation for the number of electrical outages (respectively) are
a.
2.6 and 5.77
b.
0.26 and 0.577
c.
3 and 0.01
d.
0 and 0.8
Exhibit 5-2
The probability distribution for the daily sales at Michael's Co. is given below.
Daily Sales ($1,000s)
Probability
40
0.1
50
0.4
60
0.3
70
0.2
8. Refer to Exhibit 5-2. The expected daily sales are
a.
$55,000
b.
$56,000
c.
$50,000
d.
$70,000
9. Refer to Exhibit 5-2. The probability of having sales of at least $50,000 is
a.
0.5
b.
0.10
c.
0.30
d.
0.90
Exhibit 5-3
The probability distribution for the number of goals the Lions soccer team makes per game is given below.
Number of Goals
Probability
0
0.05
1
0.15
2
0.35
3
0.30
4
0.15
10. Refer to Exhibit 5-3. What is the probability that in a given game the Lions will score at least 1 goal?
a.
0.20
b.
0.55
c.
1.0
d.
0.95
11. Refer to Exhibit 5-3. What is the probability that in a given game the Lions will score less than 3 goals?
a.
0.85
b.
0.55
c.
0.45
d.
0.80
12. Refer to Exhibit 5-3. What is the probability that in a given game the Lions will score no goals?
a.
0.95
b.
0.85
c.
0.75
d.
None of the answers is correct.
Exhibit 5-7
A sample of 2,500 people was asked how many cups of coffee they drink in the morning. You are given the following sample information.
Cups of Coffee
Frequency
0
700
1
900
2
600
3
300
2,500
13. Refer to Exhibit 5-7. The expected number of cups of coffee is
a.
1
b.
1.2
c.
1.5
d.
1.7
14. Refer to Exhibit 5-7. The variance of the number of cups of coffee is
a.
.96
b.
.9798
c.
1
d.
2.4
15. Which of the following is a characteristic of a binomial experiment?
a.
at least 2 outcomes are possible
b.
the probability of success changes from trial to trial
c.
the trials are independent
d.
All of these answers are correct.
16. The variance for the binomial probability distribution is
a.
Var(x) =p(1 -p)
b.
Var(x) =np
c.
Var(x) =n(1 -p)
d.
Var(x) =np(1 -p)
CHAPTER 6
17. The form of the continuous uniform probability distribution is
a.
triangular
b.
rectangular
c.
bell-shaped
d.
a series of vertical lines
18. For a continuous random variable x, the probability density function f(x) represents
a.
the probability at a given value of x
b.
the area under the curve at x
c.
Both the probability at a given value of x and the area under the curve at x are correct answers.
d.
the height of the function at x
19. For any continuous random variable, the probability that the random variable takes on exactly a specific value is
a.
1.00
b.
0.50
c.
any value between 0 to 1
d.
zero
20. A continuous random variable is uniformly distributed between a and b. The probability density function between a and b is
a.
zero
b.
(a-b)
c.
(b-a)
d.
1/(b-a)
21. The assembly time for a product is uniformly distributed between 6 to 10 minutes. The probability of assembling the product between 7 to 9 minutes is
a.
zero
b.
0.50
c.
0.20
d.
1
22. A standard normal distribution is a normal distribution with
a.
a mean of 1 and a standard deviation of 0
b.
a mean of 0 and a standard deviation of 1
c.
any mean and a standard deviation of 1
d.
any mean and any standard deviation
23. For a standard normal distribution, a negative value of z indicates
a.
a mistake has been made in computations, because z is always positive
b.
the area corresponding to the z is negative
c.
the z is to the left of the mean
d.
the z is to the right of the mean
24. Z is a standard normal random variable. The P(1.20 £z£ 1.85) equals
a.
0.4678
b.
0.3849
c.
0.8527
d.
0.0829
25. Z is a standard normal random variable. The P(1.05 £z£ 2.13) equals
a.
0.8365
b.
0.1303
c.
0.4834
d.
None of the alternative answers is correct.
26. Given that z is a standard normal random variable, what is the value of z if the area to the right of z is 0.1401?
a.
1.08
b.
0.1401
c.
2.16
d.
-1.08
27. Z is a standard normal random variable. What is the value of z if the area between -z and z is 0.754?
a.
0.377
b.
0.123
c.
2.16
d.
1.16
Exhibit 6-4
The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000.
28. Refer to Exhibit 6-4. What is the random variable in this experiment?
a.
the starting salaries
b.
the normal distribution
c.
$40,000
d.
$5,000
29. Refer to Exhibit 6-4. What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $30,000?
a.
0.4772
b.
0.9772
c.
0.0228
d.
0.5000
30. Refer to Exhibit 6-4. What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $47,500?
a.
0.4332
b.
0.9332
c.
0.0668
d.
0.5000
31. Refer to Exhibit 6-4. What percentage of MBA's will have starting salaries of $34,000 to $46,000?
a.
38.49%
b.
38.59%
c.
50%
d.
76.98%
a.
descriptive statistic
b.
probability function
c.
variance
d.
random variable
Explanation / Answer
1 ans ) option d random variable
2 ans) option c discrete random variable
3 ans) option a any value in an interval or collection of intervals
4 ans) option a discrete random variable
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