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Chapter 6 Practice
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 ____________ .
0.250 

0.500 

0.375 

0.000 

1.000 
Question 2
If x is uniformly distributed over the interval 8 to 12, inclusively (8 ≤ x ≤ 12), then P(x ≥ 10) is _____________ .
0.750 

0.000 

0.333 

0.500 

0.900 
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 ____________ .
0.250 

0.333 

0.375 

0.000 

1.000 
Question 4
Let z be a normally distributed random variable with mean 0 and standard deviation 1. What is P(z < 1.3)?
0.4032 

0.9032 

0.0968 

0.3485 

0. 5485 
Question 5
Let z be a normal random variable with mean 0 and standard deviation 1. What is P(z > 1.1)?
0.36432 

0.8643 

0.1357 

0.1357 

0.8643 
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.
95 

99 

68 

34 

100 
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?
0.0228 

0.9772 

0.5000 

0.4772 

1.0000 
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 ___________ .
0.1859 

0.3413 

0.8413 

0.4967 

0.5000 
Question 9
The population of lengths of aluminumcoated 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?
0.00 

0.9938 

.8289 

.5987 
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?
.0475 

.4525 

.9525 

.9554 
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?
.4525 

.2039 

.2486 

.7011 
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?
.6915 

.1915 

.5328 

.1587 
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?
0.4772 

0.9772 

0.0228 

0.5000 
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?
0.4332 

0.9332 

0.0668 

0.5000 
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?
38.49% 

38.59% 

50% 

76.98% 
Question 16
A negative value of Z indicates that
the number of standard deviations of an observation is to the right of the mean 

the number of standard deviations of an observation is to the left of the mean 

a mistake has been made in computations, since Z cannot be negative 

the data has a negative mean 
Question 17
The center of a normal curve is
always equal to zero 

is the mean of the distribution 

cannot be negative 

is the standard deviation 
Question 18
Which of the following is not a characteristic of the normal probability distribution?
The mean, median, and the mode are equal 

The mean of the distribution can be negative, zero, or positive 

The distribution is symmetrical 

The standard deviation must be 1 
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
0.4505 

0.0495 

0.9505 

0.9010 
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
0.4772 

0.9772 

0.0528 

0.5000 
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?
28.81% 

6.24% 

22.57% 

51.38% 
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)
196 

150 

249 

190 
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 Submitted On 25 Apr, 2015 04:57:03
 Smartwriter
 Rating : 5
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 Questions : 4
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