Exam 7: Continuous Probability Distributions

The distribution of the annual incomes of a group of middle management employees approximated a normal distribution with a mean of $37,200 and a standard deviation of $800. About 68% of the incomes lie between what two incomes?

The average score of 100 students taking a statistics final was 70, with a standard deviation of 7. Assuming a normal distribution, what is the probability that a student scored 90 or higher?

A major credit card company has determined that customers charge between $100 and $1,100 per month. If the average monthly amount charged is uniformly distributed, the percent of monthly charges between $600 and $889 would be ______.

Within plus and minus one standard deviation of the mean, the area under any normal curve is about 68%.

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

Some normal probability distributions are positively skewed.

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

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?

The mean of a normal probability distribution is 500 and the standard deviation is 10. About 95% of the observations lie between what two values?

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?

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

A major credit card company has determined that customers charge between $100 and $1,100 per month. If the monthly amount charged is uniformly distributed, the average charge would be ______.

The number of different standard normal distributions is unlimited.

The proportion of the area under a normal curve that is to the left of z = 0.50 is _______.

Which of the following is true in a normal distribution?

In an illustration of a normal probability distribution, a shaded area represents _______.

A major credit card company has determined that customers charge between $100 and $1,100 per month. If the average monthly amount charged is uniformly distributed, the percent of monthly changes between $311 and $889 is _______.

The proportion of the area under a normal curve that is to the right of a z score, and that is equal to zero, is ________.

Describe the uniform 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?