In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. In addition, there is a weight limit of 2,700 pounds. Assume that the average weight of students, faculty, and staff on campus is 165 pounds, that the standard deviation is 31 pounds, and that the distribution of weights of individuals on campus is approximately normal. Suppose a random sample of 16 persons from the campus will be selected. (a) What is the mean of the sampling distribution of X? (b) What is the standard deviation of the sampling distribution of X? (c) What mean weights (in pounds) for a sample of 16 people will result in the total weight exceeding the weight limit of 2,700 pounds? (d) What is the probability that a random sample of 16 people will exceed the weight limit? Step 1 (a) What is the mean of the sampling distribution of X? We are given that the average weight of students, faculty, and staff at a college is μ = 165 pounds, that the standard deviation is σ = 31 pounds, and that the distribution of weights of individuals on campus is approximately normal. We are asked to determine the mean for the sampling distribution of the sample mean, x, for a random sample of size n = 16. Recall the general property of the sampling distribution x: the mean is μ = μ. Therefore, Step 2 H= X = 1 165 165

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Chapter10: Statistics
Section10.4: Distributions Of Data
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In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. In addition, there
is a weight limit of 2,700 pounds. Assume that the average weight of students, faculty, and staff on campus is 165 pounds,
that the standard deviation is 31 pounds, and that the distribution of weights of individuals on campus is approximately
normal. Suppose a random sample of 16 persons from the campus will be selected.
(a) What is the mean of the sampling distribution of X?
(b) What is the standard deviation of the sampling distribution of X?
(c) What mean weights (in pounds) for a sample of 16 people will result in the total weight exceeding the weight limit of
2,700 pounds?
(d) What is the probability that a random sample of 16 people will exceed the weight limit?
Step 1
(a) What is the mean of the sampling distribution of X?
We are given that the average weight of students, faculty, and staff at a college is μ = 165 pounds, that the standard
deviation iso = 31 pounds, and that the distribution of weights of individuals on campus is approximately normal.
We are asked to determine the mean for the sampling distribution of the sample mean, x, for a random sample of size
n = 16.
Recall the general property of the sampling distribution x: the mean is μ = μ. Therefore, μ- = 165✓
Step 2
(b) What is the standard deviation of the sampling distribution of X?
σ- =
Recall the general property of the sampling distribution X: the standard deviation is
We are given that the
standard deviation is = 31 pounds and the random sample has size n = 16. Use these values to calculate the mean for
the sampling distribution of the sample mean.
Step 3
31 ✔
Step 5
√16
7.75✔
Step 4
We determined that the weight capacity is exceeded if 16x ≥ 2,700.
In other words, if x > 168.75
exceeded.
31
(c) What mean weights (in pounds) for a sample of 16 people will result in the total weight exceeding the weight limit
of 2,700 pounds?
Since the elevator holds a maximum of 16 people and the average weight of each person is x, the weight capacity of
2,700 pounds will be exceeded when 16 ✔
16 x ≥ 2,700.
7.75
H=165
- = 7.75
(d) What is the probability that a random sample of 16 people will exceed the weight limit?
P(x ≥ b) =
P(X ≥ 168.75) =
=
An elevator at a college has a posted weight limit of 2,700 pounds, and a maximum capacity of 16 people. We determined
that if the sample mean x ≥ 168.75 for a particular sample of 16 people, then the weight capacity will be exceeded. We are
asked to determine the probability that a random sample of 16 people will exceed the weight limit.
We previously determined the mean and standard deviation of the sampling distribution of X.
- P(Z = b =#=)
pzz
We are given that the distribution of weights of individuals on campus is approximately normal, so the sampling distribution
of X is approximately normal also. We can calculate the desired probability by standardizing. Recall the standardization
formula.
= 1 -
In other words, we need to find the following. (Round your answer to four decimal places.)
6
168.75 ✔
168.75 - 165
0.4839
=
- P(Z ≤ 0.1916 X
0
168.75 for a particular sample of 16 people, then the weight capacity will be
7.75
P(X 168.75) = 1 - P(Z < 0.4839)
= 1-90.1916
10 0.8086
165.
X
X
0.4839
0.4839
Step 6
Use technology to find the cumulative probability associated with a particular z-score, rounding the result to four decimal
places.
Transcribed Image Text:In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. In addition, there is a weight limit of 2,700 pounds. Assume that the average weight of students, faculty, and staff on campus is 165 pounds, that the standard deviation is 31 pounds, and that the distribution of weights of individuals on campus is approximately normal. Suppose a random sample of 16 persons from the campus will be selected. (a) What is the mean of the sampling distribution of X? (b) What is the standard deviation of the sampling distribution of X? (c) What mean weights (in pounds) for a sample of 16 people will result in the total weight exceeding the weight limit of 2,700 pounds? (d) What is the probability that a random sample of 16 people will exceed the weight limit? Step 1 (a) What is the mean of the sampling distribution of X? We are given that the average weight of students, faculty, and staff at a college is μ = 165 pounds, that the standard deviation iso = 31 pounds, and that the distribution of weights of individuals on campus is approximately normal. We are asked to determine the mean for the sampling distribution of the sample mean, x, for a random sample of size n = 16. Recall the general property of the sampling distribution x: the mean is μ = μ. Therefore, μ- = 165✓ Step 2 (b) What is the standard deviation of the sampling distribution of X? σ- = Recall the general property of the sampling distribution X: the standard deviation is We are given that the standard deviation is = 31 pounds and the random sample has size n = 16. Use these values to calculate the mean for the sampling distribution of the sample mean. Step 3 31 ✔ Step 5 √16 7.75✔ Step 4 We determined that the weight capacity is exceeded if 16x ≥ 2,700. In other words, if x > 168.75 exceeded. 31 (c) What mean weights (in pounds) for a sample of 16 people will result in the total weight exceeding the weight limit of 2,700 pounds? Since the elevator holds a maximum of 16 people and the average weight of each person is x, the weight capacity of 2,700 pounds will be exceeded when 16 ✔ 16 x ≥ 2,700. 7.75 H=165 - = 7.75 (d) What is the probability that a random sample of 16 people will exceed the weight limit? P(x ≥ b) = P(X ≥ 168.75) = = An elevator at a college has a posted weight limit of 2,700 pounds, and a maximum capacity of 16 people. We determined that if the sample mean x ≥ 168.75 for a particular sample of 16 people, then the weight capacity will be exceeded. We are asked to determine the probability that a random sample of 16 people will exceed the weight limit. We previously determined the mean and standard deviation of the sampling distribution of X. - P(Z = b =#=) pzz We are given that the distribution of weights of individuals on campus is approximately normal, so the sampling distribution of X is approximately normal also. We can calculate the desired probability by standardizing. Recall the standardization formula. = 1 - In other words, we need to find the following. (Round your answer to four decimal places.) 6 168.75 ✔ 168.75 - 165 0.4839 = - P(Z ≤ 0.1916 X 0 168.75 for a particular sample of 16 people, then the weight capacity will be 7.75 P(X 168.75) = 1 - P(Z < 0.4839) = 1-90.1916 10 0.8086 165. X X 0.4839 0.4839 Step 6 Use technology to find the cumulative probability associated with a particular z-score, rounding the result to four decimal places.
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