Exam 7: Continuous Probability Distributions

A national manufacturer of unattached garages discovered that the distribution of the time for two construction workers to erect the Red Barn model is normally distributed with a mean of 32 hours and a standard deviation of 2 hours. What percent of the garages take between 32 and 34 hours to erect?

After arriving at the university student medical clinic, the waiting times to receive service after checking-in follow an exponential distribution with a mean of 10 minutes. Fifty percent of the students wait less than how many minutes?

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

A new extended-life light bulb has an average life of 750 hours, with a standard deviation of 50 hours. If the life of these light bulbs approximates a normal distribution, about what percent of the distribution will be between 600 hours and 900 hours?

What is the area under the normal curve between z = -1.0 and z = -2.0?

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?

For a uniformly distributed random variable, x, P(x) = 1/(b - a).

Non-stop Airlines determined that the mean number of passengers per flight is 152 with a standard deviation of 10 passengers. Practically all flights have between 142 and 162 passengers.

The exponential distribution is applied to situations characterized by _______.

The mean of a normal distribution is 400 pounds. The standard deviation is 10 pounds. What is the probability of a weight between 415 pounds and the mean of 400 pounds?

For the standard normal distribution, the z-score that corresponds with the first quartile is ________.

A binomial distribution has 50 trials (n = 50) with a probability of success of 0.50 (π = 0.50). We would like to find the probability of 34 or more successes using the normal distribution to approximate the binomial. Applying the continuity correction factor, what z-score should be used?

To apply the normal approximation to a binomial distribution, mean, and variance are ________.

The number of different standard normal distributions is unlimited.

The mean of a normal probability distribution is 60 and the standard deviation is 5. The percent of observations that are between 50 and 70 is ______.

For the normal distribution, the mean plus and minus two standard deviations will include about what percent of the observations?

If an average of 12 customers are served per hour, then one customer arrives every ________.

The proportion of the area under a normal curve that is to the left of z = 1.40 is _______.

The weight of a bag of corn chips is normally distributed with a mean of 22 ounces and a standard deviation of 0.5 ounces. The probability that a bag of corn chips weighs between 20.75 and 23.25 ounces is ____.

What is special about the standard normal distribution?