stats test 3

Find the z-score for which the area under the standard normal curve to its left is 0.40?

-0.25

For a standard normal curve, find the z-score that separates the bottom 30% from the top 70%?

-0.53

Find the z-score having area 0.86 to its right under the standard normal curve; that is, find z0.86?

-1.08

Determine the two z-scores that separate the middle 96% of the distribution from the area in the tails of the standard normal distribution?

-2.05 and 2.05

The graph of a normal curve is given. Use the graph to identify the value of _ and _?

-6, 2

The tread of life of a particular brand of tire is a random variable best described by a normal distribution with a mean of 60,000 miles and a standard deviation of 1100 miles. What is the probability a particular tire of this brand will last longer than 58,900 miles?

0.8413

Assume that the random variable X is normally distributed, with mean _ = 90 and standard deviation _ = 12. Compute the probability P(57 < X < 105)?

0.8914

Assume that the random variable X is normally distributed, with mean _ = 80 and standard deviation _ = 8. Compute the probability P(X<90)?

0.8944

Find the area under the standard normal curve to the right of z = -1.25

0.8944

Find the area under the standard normal curve to the left of z = 1.5?

0.9332

Suppose a population has a mean of 7 for soem characteristic of interest and a standard deviation of 9.6. A sample is drawn fro mthis population of size 64. What is the standard error of the mean?

1.2

For a standard normal curve, find the z-score that separates the bottom 90% from the top 10%?

1.28

Find the z-score for which the area under the standard normal curve to its right is 0.07?

1.48

z0.05

1.645

Find the z-score for which the area under the standard normal curve to its left is 0.96?

1.75

suppose a brewery ..... 12 ounce bottles of beer. ..... normal distribution mean of 12.23 ounces and standard deviation of 0.04 ounce. the company is interested in reducing the amount of extra beer that is poured into the 12 ounce bottles. The company is seeking to identify the highest 1.5% of the fills amounts poured by this machine. For what fill amount are they searching? Round to the nearest thousandth

12.317

The sampling distribution of the sample mean is shown. If the sample size is n = 36, what is the standard deviation of the population from which the sample was drawn? Round to the nearest thousandth where appropriate

240

_ = 25, _ = 12, _ = 16

25, 3

The amount of corn chips dispensed into a 32-ounce bag by the dispensing machine has been identified as possesing a normal distribution with a mean of 32.5 ounces and a standard deviation of 0.2 ounce. What chip amount represents the 67th percentile for the bag weight distribution? Round to the nearest hundredth

32.59 oz

A new phone system was installed last year to help reduce the expense of personal calls that were being made by employees. Before the new system was installed, the amount being spent on personal calls follows a normal distribution with an average of $700 per month and a standard deviation of $50 per month. Refer to such expenses as PCE's (personal call expenses). Find the probability that a randomly selected month had a PCE that falls below $550?

0.0013

A physical fitness association is including the mile run in its secondary school fitness test. The time for this event for boys in secondary school is known to possess a normal distribution with a mean of 460 seconds and a standard deviation of 40 seconds. Find the probability that a randomly selected boy in secondary school can run the mile in less than 368 seconds?

0.0107

Suppose a brewery has a filling machine follows a normal distribution with a mean of 12.36 ounces and a standard deviation of 0.04 ounce. Find the probability that the bottle contains between 12.26 and 12.32 ounces?

0.1525

Find the area under the standard normal curve to the right z = 1?

0.1587

The amount of soda a dispensing machine pours into a 12 ounce can of soda follows a normal distribution with a mean of 12.24 ounces and a standard deviation of 0.16 ounce. The cans only hold 12.40 ounces of soda. Every can that has more than 12.40 ounces of soda poured into it causes a spill and the can needs to go through a special cleaning process before it can be sold. What is the probability of a randomly selected can will need to go through this process?

0.1587

Assume that the random variable X is normally distributed, with mean _ = 110 and standard deviation _ = 20. Compute the probability P(X>126)?

0.21119

Suppose a brewery has a filled machine that fills 12 ounce bottles of beer. It is known that the amount of beer poured by this filling machine follows a normal distribution with a mean of 12.14 onces and a standard deviation of 0.04 ounce. Find the probability that the bottle contains more than 12.14 ounces of beer?

0.4

Find the area under the standard normal curve between z = 0 and z = 3?

0.4987

For a standard normal curve, find the z-score that separates the bottom 70% from the top 30%?

0.53

High temperatures in a certain city for the month of august follow a uniform distribution over the 66 F to 85 F. What is the probability that a randomly selected August day has a high temperature that exceeded 71 F?

0.7368

Assume that the random variable X is normally distrubed with mean _ = 50 and standard deviation _ = 12. Find the 40th percentile for X.

47

A physical fitness association is includeing the mile run..... the time for this event .... posesses a normal distribution with a mean of 460 seconds and standard deviation of 60 seconds. The fitness association wants to recognize the boys whose times are among the top (or fastest) 10% with certificates of recognition. What time would the boys need to beat in order to earn a certificate of recognition from the fitness association?

536.8

Approximately ____________ % of the area under the normal curve is between _ - 2_ and _ +2_?

95

Industrial psychologist 40 employee experiment "Its great to be awake (a or b)

Normally distributed (B)

The following data represent a random sample of the number of shares of a pharmaceutical company's stock traded for 20 days in 2000.

Not normally distributed (B)

Compare a graph of the normal density function with mean of 0 and standard deviation of 1 with a graph of a normal density function with mean equal to 4 and standard deviation of 1. The graphs would?

Have the same height but one would be shifted 4 units to the right