Exam 7: Continuous Probability Distributions

Consider a continuous random variable x,which is uniformly distributed between 65 and 85. The probability of x taking on a value between 75 to 90 is ________.

A large manufacturing firm tests job applicants. Test scores are normally distributed with a mean of 500 and a standard deviation of 50. Management is considering placing a new hire in an upper-level management position if the person scores in the upper sixth percent of the distribution. What is the lowest score a new hire must earn to qualify for a responsible position?

Customers of the Key Refining Company charge an average of $70 per month. The distribution of amounts charged is approximately normal,with a standard deviation of $10. What is the probability of selecting a credit card customer at random and finding the customer charged between $70 and $83?

The standard deviation of any uniform probability distribution is ________.

The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the probability that a flight is less than 135 minutes?

Suppose a tire manufacturer wants to set a mileage guarantee on its new XB 70 tire. Tests revealed that the tire's mileage is normally distributed with a mean of 47,900 miles and a standard deviation of 2,050 miles. The manufacturer wants to set the guaranteed mileage so that no more than 5% of the tires will have to be replaced. What guaranteed mileage should the manufacturer announce?

Tables of normal distribution probabilities are found in many statistics books. These probabilities are calculated from a normal distribution with ________.

A college professor noted that the grades of his students in an introductory statistics class were normally distributed with a mean of 76.5 and a standard deviation of 9. If 67.36% of his students received grades of C or above,what is the minimum score of those students receiving a grade of at least a C?

The exponential distribution is a probability distribution for a random variable measured as a rate of an event occurring.

Two normal distributions are compared. One has a mean of 10 and a standard deviation of 10. The second normal distribution has a mean of 10 and a standard deviation of 2. Which of the following is true?

When referring to the normal probability distribution,there is not just one; there is a "family" of normal probability distributions.

A cola-dispensing machine is set to dispense a mean of 2.02 liters into a container labeled 2 liters. Actual quantities dispensed vary,and the amounts are normally distributed with a standard deviation of 0.015 liters. What is the probability a container will have less than 2 liters?

A "continuity correction factor" is used to compute probabilities when using the normal distribution to approximate the binomial distribution.

An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation of the distribution was 1.2 hours. About 95.44% of the batteries failed between what two values?

The standard normal probability distribution is unique because it has ________.

The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the probability that a flight is between 125 and 140 minutes?

Which of the following is true in a normal distribution?

Which of the following is true regarding the normal distribution?

A binomial distribution has 100 trials (n = 100)with a probability of success of 0.25 (π = 0.25). We would like to find the probability of 75 or more successes using the normal distribution to approximate the binomial. Applying the continuity correction factor,what value would be used to calculate a z-score?

The annual commissions per salesperson employed by a retailer of mobile communication devices averaged $40,000,with a standard deviation of $5,000. What percent of the salespersons earn between $32,000 and $42,000?