11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
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MATH1123, section OB, Fall 2023
Chapter 6 Quiz (Quiz)
INSTRUCTOR
Hua He
Hawaii Paci�c University
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SUN, NOV 19, 2023
11:59 PM HST
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11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177290 2/7
Classify each of the following random variables as either discrete or continuous.
(a) the fuel efficiency (miles per gallon) of an automobile
(b) the amount of rainfall at a particular location during the next year
(c) the distance that a person throws a baseball
(d) the number of strokes in a round of golf
(e) the weight (in ounces) of an apple
(f) the amount of water used by a household during a given month
(g) the number of traffic citations issued by the highway patrol in a particular county on a given day
discrete
continuous
discrete
continuous
discrete
continuous
discrete
continuous
discrete
continuous
discrete
continuous
discrete
continuous
1. [7/7 Points] PECKSTAT3 6.1.004.DETAILS PREVIOUS ANSWERS MY NOTES
11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
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A person is asked to draw a line segment that they think is 7 inches long. The length of the line segment drawn will be
measured, and the value of x = (Actual length − 7) will be calculated.
(a) What is the value of x for a person who draws a line segment that is 7.3 inches long?
(b) Is x a discrete or continuous random variable? Explain.
This random variable is continuous since the possible values of x are all points in some interval .
A pizza shop sells pizzas in four different sizes. The 1,000 most recent orders for a single pizza resulted in the following
proportions for the various sizes.
Size (inches) 12 14 16 18
Proportion 0.12 0.33 0.49 0.06
With x = Size of a pizza in a single-pizza order, the given table is an approximation to the probability distribution of x.
(a) Write a few sentences describing what you would expect to see for pizza sizes over a long sequence of single-pizza
orders. (Give your answers as percents.)
In the long run, we would expect to see approximately % of the single-pizza orders for 12 inch pizza,
% for 14 inch pizza, % for 16 inch pizza, and % for 18 inch pizza.
(b) What is the approximate value of
(c) What is the approximate value of
P(x < 16)?
P(x ≤ 16)?
2. [2/3 Points] PECKSTAT3 6.1.008.MI.DETAILS PREVIOUS ANSWERS MY NOTES
3. [–/6 Points] PECKSTAT3 6.2.015.DETAILS MY NOTES
11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
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An appliance dealer sells three different models of upright freezers having 13.3, 16.1, and 19.3 cubic feet of storage space.
Consider the random variable x = Amount of storage space purchased by the next customer to buy a freezer. Suppose that x
has the following probability distribution.
x p(x)
13.3 0.2
16.1 0.5
19.3 0.3
(a) Calculate the mean and standard deviation of x (in cubic feet). (Hint: See Example 6.15. Round your standard deviation
to four decimal places.)
= cubic ft
= cubic ft
(b) Give an interpretation of the mean and standard deviation of x in the context of observing the outcomes of many
purchases.
The mean represents the long run average distribution of freezers sold by this particular appliance dealer. The
standard deviation represents a typical deviation in how much the distribution in freezers purchased deviates from
the mean.
The mean represents the long run average number of freezers sold by this particular appliance dealer. The standard
deviation represents a typical deviation in how many freezers purchased deviates from the mean.
The mean represents the long run average cost of freezers sold by this particular appliance dealer. The standard
deviation represents a typical deviation in how much is spent on freezers purchased deviates from the mean.
The mean represents the long run average type of freezer sold by this particular appliance dealer. The standard
deviation represents a typical deviation in what type of freezer purchased deviates from the mean.
The mean represents the long run average storage space of freezers sold by this particular appliance dealer. The
standard deviation represents a typical deviation in how much the storage space in freezers purchased deviates
from the mean.
????x
????x
4. [–/3 Points] PECKSTAT3 6.4.033.DETAILS MY NOTES
11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
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Suppose that for a given computer salesperson, the probability distribution of
x = Number of systems sold in one week
is given by the following table.
x 1 2 3 4 5 6 7 8
p(x) 0.04 0.10 0.13 0.30 0.29 0.12 0.01 0.01
(a) Find the mean value of x (the mean number of systems sold).
(b) Find the variance and standard deviation of x. (Round your standard deviation to four decimal places.)
variance
standard deviation
How would you interpret these values? (Round your standard deviation to four decimal places.)
The mean squared deviation from the mean number of systems sold in one week is . A typical deviation
from the mean number of systems sold in one week is .
(c) What is the probability that the number of systems sold is within 1 standard deviation of its mean value?
(d) What is the probability that the number of systems sold is more than 2 standard deviations from the mean?
5. [–/7 Points] PECKSTAT3 6.4.036.MI.DETAILS MY NOTES
11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
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Let z denote a random variable that has a standard normal distribution. Determine each of the probabilities below. (Round your
answers to four decimal places.)
(a) P(z < 2.39)
(b) P(z ≤ 2.39)
(c)
(d)
(e)
(f) P(z > 1)
(g)
(h) P(z < 4.97)
P(z < −1.24)
P(1.13 < z < 3.34)
P(−0.78 ≤ z ≤ −0.53)
P(z ≥ −3.37)
6. [–/8 Points] PECKSTAT3 6.5.042.S.DETAILS MY NOTES
11/17/23, 10:30 PM Chapter 6 Quiz – MATH1123, section OB, Fall 2023 | WebAssign
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Purchases made at small “corner stores” were studied by the authors of a certain paper. Corner stores were defined as stores
that are less than 200 square feet in size, have only one cash register, and primarily sell food. After observing a large number
of corner store purchases in Philadelphia, the authors reported that the average number of grams of fat in a corner store
purchase was 21.2. Suppose that the variable
x = Number of grams of fat in a corner store purchase
has a distribution that is approximately normal with a mean of 21.2 grams and a standard deviation of 6 grams. (Round your
answers to four decimal places.)
(a) What is the probability that a randomly selected corner store purchase has more than 31 grams of fat?
(b) What is the probability that a randomly selected corner store purchase has between 15 and 25 grams of fat?
(c) If two corner store purchases are randomly selected, what is the probability that both of these purchases will have more
than 25 grams of fat?
A machine producing vitamin E capsules operates so that the actual amount of vitamin E in each capsule is normally distributed
with a mean of 4 mg and a standard deviation of 0.1 mg. (Round your answers to four decimal places.)
What is the probability that a randomly selected capsule contains less than 3.8 mg of vitamin E?
What is the probability that a randomly selected capsule contains at least 4.5 mg of vitamin E?
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7. [–/3 Points] PECKSTAT3 6.5.050.MI.S.DETAILS MY NOTES
8. [–/2 Points] PECKSTAT3 6.5.061.S.DETAILS MY NOTES