Exam 7: Continuous Probability Distributions

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

Describe the normal distribution.

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

A major credit card company has determined that customers charge between $100 and $1100 per month. Given that the average monthly amount charged is uniformly distributed, what is the 3^rd quartile of the distribution? _____________

The z-scores for X values greater than the mean are negative.

The annual commissions per salesperson employed by a manufacturer of light machinery averaged $40,000 with a standard deviation of $5,000. What percent of the sales persons earn between $32,000 and $42,000?

Some normal probability distributions are positively skewed.

Two business major students, in two different sections of an economics class, were comparing test scores. The following gives the students scores, class mean, and standard deviation for each section. What is the z-score of the student from section 2? _____________

The mean of a normally distributed group of weekly incomes of a large group of executives is $1,000 and the standard deviation is $100. What is the z-score for an income of $1,100?

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?

A major credit card company has determined that customers charge between $100 and $1100 per month. Given that the average monthly amount charged is uniformly distributed, what is the standard deviation of the monthly amount charged? _________

For the normal distribution, the mean plus and minus 1.96 standard deviations will include about what percent of the observations?

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?

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. How many students are served per hour?

The employees of Cartwright Manufacturing are awarded efficiency ratings. The distribution of the ratings approximates a normal distribution. The mean is 400, the standard deviation 50. What is the area under the normal curve between 400 and 482?

Which of the following is a characteristic of the normal probability distribution?

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?

A sample of 500 evening students revealed that their annual incomes were normally distributed with a mean income of $30,000 and a standard deviation of $3,000. How many students earned more than $36,000? _______

If an average of 12 customers is served per hour, what is the probability that the next customer will arrive in 3 minutes or more?

What proportion of the area under a normal curve is to the right of z = -1.71? ________