Exam 7: Continuous Probability Distributions

The standardized z value measures distance between an outcome, X, and the mean by the number of _____________________.

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?

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. Calculate the probability a student waits between 8 and 12 minutes.

A binomial distribution has 50 trials (n = 50) with a probability of success of 0.50 ( $\pi$ =0.50). To use the normal distribution to approximate the binomial, what are the mean and standard deviation?

Ball-Bearings, Inc. produces ball bearings automatically on a Kronar BBX machine. For one of the ball bearings, the mean diameter is set at 20.00 mm (millimeters). The standard deviation of the production over a long period of time was computed to be 0.150 mm. What percent of the ball bearings will have diameters 20.27 mm or more?

The number of different standard normal distributions is unlimited.

The average score of 100 students taking a statistics final was 70 with a standard deviation of 7. Assuming a normal distribution, what test score separates the top 25% of the students from the lower 75% of students?

For a uniform probability distribution, the probability of any event is equal to 1/(b-a).

The mean of a normal probability distribution is 60 and the standard deviation is 5. What percent of observations are between 50 and 70? ________%

Which of the following is true regarding the normal distribution?

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 percent of the incomes lie between what two incomes?

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

A study conducted by a local tennis center revealed that 25 percent of its new members have novice level tennis skills. A membership drive in a metropolitan area resulted in 500 new members. What is the probability that 110 or less of the new members are novice tennis players?

The upper and lower limits of a uniform probability distribution are

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 standard deviation?

The weight of cans of fruit is normally distributed with a mean of 1,000 grams and a standard deviation of 50 grams. What percent of the cans weigh 860 grams or less?

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

In a uniform distribution, with a minimum, a, and maximum, b, the probability that the random variable, x, is between a and (b - a)/2 is ___________.

The mean amount spent by a family of four on food per month is $500 with a standard deviation of $75. Assuming that the food costs are normally distributed, what is the probability that a family spends less than $410 per month?

The mean amount of gasoline and services charged by Key Refining Company credit customers is $70 per month. The distribution of amounts spent 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?