Historical data is used if you are doing a _________ study. - Answers Retrospective
If you go out to collect data to analyze, this would be an example of a ________ study. - Answers
observational
The Addition Rule states that P(A U B) = P(A) + P(B) - _________. - Answers P(A∩B)
The variance formula for a random variable with the Discrete Uniform pmf will only work if the values
of the random variable are __________ integers. - Answers Consecutive
Recall that in class, we talked about discrete and continuous random variables. Which of the follwoing
would be a good example of a continuous random variable?
a) Number of defects on a circuit board.
b) Number of cars passing in an intersection.
c) A student's GPA as reported on their transcript.
d) The face value for the throw of a fair die.
e) The height of a person - Answers Height
Consider a discrete random variable. Which of the following, when plotted will look like stairs going
up and to the right? - Answers F(X)
Consider a discrete random variable X, with range x= 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. P(X < 10) = F( ). What
number should be in the parenthesis after "F"? - Answers 9
Width measuremetns of a steel bar are made to the nearest hundreth of a millimeter. The thickness
measurements are discrete uniformly distributed with values 1mm, 2mm, 3mm, and 4mm. E(X) = 2.5
mm.
a) What is the expected value of a discrete random variable, X.
b) What is the units? - Answers a) 2.5
b) mm
Which of the following probability distributions often determines the probabilities of a counting
process? - Answers Poisson Distribution
An electronic product contains 51 integrated circuits. The probability that any integrated circuit is
defective is 0.01, and the integrated circuits are independent. Suppose you want to determine the
probability that the number of defective circuits in this product is equal to 2. The best definition of the
random variable, X, in words is: - Answers X is the number of defective integrated circuits out of 51
integrated circuits.
Explanation: X is a binomial random variable, not a probability.
We know that ________ will always have one of two outcomes. - Answers A Bernoulli Trial
A side door panel on a vehicle is produced at Acme Co. Twenty-five of these doors are inspected to
determine if they pass or fail. The probability that a door passes is 0.83. Suppose you want to
determine the probability that the number of doors that pass our of these 25 is equal to 19. The best
definition of the random variable, X, in words is: - Answers X is the number of doors out of 25 that
pass.
p(x) is the notation for pmf of a discrete random variable. We also know that F(X) is the notation for a
CDF, the cumulative distribtuion function. If X is a discrete random variable, what is true?
a) F(X) >= p(X)
b) F(x) and p(x) can be negative
c) p(x) and F(X) can be > 1
d) p(x) and F(x) represent the same quantities for all values of x.
e) p(x) >= F(X) - Answers a) F(X) >= p(X)
T or F: X is the weight in grams of a gear used in the rotary mechanism of a microwave oven. The pdf
is given as f(x) = 1/3 for 3.5 gram < x < 6.5 grams. X is a continuous variable. - Answers True
X is the weight in grams of a gear used in the rotary mechanism of a microwave oven. The pdf is given
as f(x) = 1/3 for 3.5 gram < x < 6.5 grams. The probability that the weight of one of these parts is equal
to 5 grams is: - Answers 0
A standard normal variable is ________. - Answers A Contnuous Random Variable
The probability that random variable Z = 0 is: - Answers 0
E(X^2) - [E(X)]^2 is: - Answers The variance of x
T or F: Both Z and T have ranges from -infinity to +infinity. - Answers True