Exam 7: Continuous Probability Distributions

Which of the following is NOT a characteristic of the normal probability distribution?

For a normal probability distribution,about 95 percent of the area under normal curve is within plus and minus two standard deviations of the mean and practically all (99.73 percent)of the area under the normal curve is within three standard deviations of the mean.

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

The z-scores for X values less than the mean are positive.

Areas within a continuous probability distribution represent probabilities.

A financial advising company has determined that the price-to-earnings ratios for 20 randomly selected publicly traded companies range between 0.9 and 2.9.Given that the price-to-earnings ratios are uniformly distributed,what percent of price-to-earnings ratios are less than 0.9? _____________

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

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 greater than 65?

The total area within a continuous probability distribution is equal to 100.

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?

Identify two similarities of the uniform and normal distributions.

For any uniform probability distribution,the mean and standard deviation can be computed by knowing the maximum and minimum values of the random variable.

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?

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?

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 financial advising company has determined that the price-to-earnings ratios for 20 randomly selected publicly traded companies range between 0.9 and 2.9.Given that the price-to-earnings ratios are uniformly distributed,what percent of price-to-earnings ratios are equal to 2.58? __________

What is a graph of a normal probability distribution called? _________

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

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 5% of the students from the lower 95% of students?

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