Question 1
If x is uniformly distributed over the interval 8 to 12, inclusively (8 ≤ x ≤ 12), then the probability, P(13 ≤ x ≤ 15), is ____________ .
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0.250
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0.500
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0.375
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0.000
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1.000
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Question 2
If x is uniformly distributed over the interval 8 to 12, inclusively (8 ≤ x ≤ 12), then P(x ≥ 10) is _____________ .
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0.750
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0.000
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0.333
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0.500
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0.900
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Question 3
If x, the time (in minutes) to complete an change job at certain auto service station, is uniformly distributed over the interval 20 to 30,
inclusively (20 ≤ x ≤ 30), then the probability that an oil change job is completed in 21.75 to 24.25 minutes, inclusively, i.e., P(21.75 ≤
x ≤ 24.25) is ____________ .
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0.250
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0.333
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0.375
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0.000
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1.000
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Question 4
Let z be a normally distributed random variable with mean 0 and standard deviation 1. What is P(z < 1.3)?
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0.4032
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0.9032
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0.0968
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0.3485
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0. 5485
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Question 5
Let z be a normal random variable with mean 0 and standard deviation 1.
What is P(z > -1.1)?
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0.36432
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0.8643
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0.1357
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-0.1357
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-0.8643
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Question 6
Within a range of z scores from -1 to +1, you can expect to find ______ percent of the values in a normal distribution.
Question 7
Sure Stone Tire Company has established that the useful life of a particular brand of its automobile tires is normally distributed with a mean of 40,000 miles and a standard deviation of 5000 miles.
What is the probability that a randomly selected tire of this brand has a life of at least 50,000 miles?
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0.0228
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0.9772
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0.5000
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0.4772
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1.0000
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Question 8
The net profit of an investment is normally distributed with a mean of $10,000 and a standard deviation of $5,000.
The probability that the investor's net gain will be at least $5,000 is ___________ .
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0.1859
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0.3413
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0.8413
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0.4967
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0.5000
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Question 9
The population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.5 inches and a standard deviation of 0.2 inches.
What is the probability that a sheet selected at random will be less than 31 inches long?
Question 10
An apple juice producer buys all his apples from a conglomerate of apple growers in one northwest state.
The amount of juice squeezed from each of these apples is approximately normally distributed with a mean of 2.25 ounces and a standard deviation of 0.15 ounce.
What is the probability that a randomly selected apple will contain between 2.00 and 3.00 ounces?
Question 11
An apple juice producer buys all his apples from a conglomerate of apple growers in one northwest state.
The amount of juice squeezed from each of these apples is approximately normally distributed with a mean of 2.25 ounces and a standard deviation of 0.15 ounce.
What is the probability that a randomly selected apple will contain between 2.00 and 2.15 ounces?
Question 12
A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.
What percentage of the time will the number of boxes received weekly be between 180 and 210?
Question 13
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.
What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $30,000?
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0.4772
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0.9772
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0.0228
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0.5000
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Question 14
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.
What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $47,500?
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0.4332
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0.9332
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0.0668
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0.5000
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Question 15
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.
What percentage of MBA's will have starting salaries of $34,000 to $46,000?
Question 16
A negative value of Z indicates that
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the number of standard deviations of an observation is to the right of the mean
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the number of standard deviations of an observation is to the left of the mean
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a mistake has been made in computations, since Z cannot be negative
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the data has a negative mean
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Question 17
The center of a normal curve is
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always equal to zero
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is the mean of the distribution
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cannot be negative
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is the standard deviation
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Question 18
Which of the following is not a characteristic of the normal probability distribution?
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The mean, median, and the mode are equal
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The mean of the distribution can be negative, zero, or positive
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The distribution is symmetrical
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The standard deviation must be 1
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Question 19
The weight of football players is normally distributed with a mean of 200 pounds and a standard deviation of 25 pounds.
The probability of a player weighing more than 241.25 pounds is
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0.4505
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0.0495
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0.9505
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0.9010
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Question 20
The weight of football players is normally distributed with a mean of 200 pounds and a standard deviation of 25 pounds.
The probability of a player weighing less than 250 pounds is
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0.4772
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0.9772
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0.0528
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0.5000
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Question 21
The weight of football players is normally distributed with a mean of 200 pounds and a standard deviation of 25 pounds.
What percent of players weigh between 180 and 215 pounds?
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28.81%
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6.24%
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22.57%
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51.38%
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Question 22
The weight of football players is normally distributed with a mean of 200 pounds and a standard deviation of 25 pounds.
What is the minimum weight of the middle 95% of the players? (HINT: Apply the Empirical Rule to solve this question)