chapter 6 Stat Problems

Finding the z value that corresponds to given area #45 (6-1)

-1.26

Finding the z value that corresponds to given area #43 (6-1)

-2.0791

Find the area under standard normal distribution curve: P(z>2.83)

0.0023

the average repair cost of a micro wave is 55, with a stand. dev. of 8. The cost are normally distributed if 12 ovens are repaired find the probability that the mean of the repair bills will be greater than 60.

0.015

Find the area under standard normal distribution curve z=-1.56 and z=-1.83

0.0258

If 8% of all people in a certian geographic region are unemployed find the probability that in a sample of 200 people there are fewer than 10 people who are employed.

0.0455

38% of Americans get 6 hrs or less of sleep each night if 25 people are selected find the probablility that in a sample of 14 or more will get 6hrs or less of sleep each night #29 studguide

0.0495

53% of us households have a personal computer in a random sample of 250 households what is the probability that fewer than 120 have a PC (32 SG)

0.0495

Find the area under standard normal distribution curve P(1.46<z<2.97)

0.0707

Find the area under standard normal distribution curve to the left of z=-1.39

0.0823

Find the area under standard normal distribution curve between z=1.05 and z=1.78

0.1093

Find the area under standard normal distribution curve p(0<z<0.67)

0.2486

Find the area under standard normal distribution curve, between z=0 and z=0.75 (6-1)

0.2734

Find the area under standard normal distribution curve to the right of z=1.92 and to the left of z=-0.44 (1.6 #25)

0.3574

Find the area under standard normal distribution curve to the right z=0.29

0.3859

A theater owner had found that 5% of patrons do not show up for the performance that they purchased tickets for. If the the theater has 100 seats, find the probability that 6 or more patrons will not show up for the sold out performance.

0.4090

Find the area under standard normal distribution curve P(-1.43<z<0)

0.42364

Find the area under standard normal distribution curve, between Z=0 and z=-2.07

0.4808

Use standard normal distribution p(0<z<2.16)

0.4846

Find the area under standard normal distribution curve to the right of z=-0.17

0.5675

percentage of US households that have online connections is 44.9% in a random sample of 420 households, what is the probability that fewer than 200 have a online connection

0.8577

Find the area under standard normal distribution curve P(-2.46<Z<1.74) #35 6-1

0.9521

The average electricbill in a residential area is 72$ for the month of April . The standard dev is 6$. If amounts of electric bills are normally distributed find the probablity that the mean of the bill for 15 residents will be less then 75$.

0.9738

Find the area under standard normal distribution curve to the left of z=2.11

0.9826

Finding the z value that corresponds to given area #41 (6-1)

1.39

Average thickness of books on a shelf is 8.3 cm. The stand. dev is 0.6. If 26% of the books are oversized find he the minimum thickness of the oversized books on the shelf.

8.804

Find the z value to the left of the mean so that: a) 98.87% of the area under the distribution curve lies to the right of it. b) 83.12% of the area under the distribution curve lies to the right of it. c)60.64% of the area under the distribution curve lies to the right of it. (6-1)

a)-0.2801 b)0.91995 c)0.26995

the avg # of yrs to complete a grad. program is 3. The standard dev. 4 month. if an individual enrolls in the program find the probability they will take a) more than 4 yrs b)less then 3 yrs c)between 3.8 and 4.5 yrs d)between 2.5 and 3.1 yrs

a)0.0013 b)0.5 c)0.0082 d)0.5511

on the daily run of the express bus the avg # of passengers is 48. The standard dev. is 3. Assume the variable is normally distributed. Find the probability that the bus will have a) between 36 and 40 b)fewer than 42 c)more than 48 d) between 43 and47

a)0.0038 b)0.0228 c)0.4999 d)0.3232

The avg. height of a certian age group of people is 53 in. The standard deviation is 4 in. If the variable is normally distributed find the probability that a selected individuals height will be a)greater then 59 in b)less than 45 c)between 50 and 55

a)0.0668 b)0.0228 c)0.4648

The avergage salary for graduates entering the actuarial fiel is 40,000. if the salaries are normally distributed with a standard deviation of 5000, find the probability that : a)an individual graduate will have a salary over 45,000 b)a sample of nine graduates will have an average over 45000.

a)0.1587 b)0.0013

the avg. # of gallons of lemonade consumed during a game is 20 with standard dev. of 3. Assume variable is normally distributed when a game is played. Find the probability of using a) between 20 and 25 gallons b) less than 19 gallons c)more than 21 gallons d)between 26 and 28 gallons

a)0.4525 b)0.3707 c)0.3707 d)0.0190

The average commute to work one way is 25 min. according to the 2005 Amarican community survey. if we assume that commuting times are normally distributed and that the standard dev. is 6.1 min. what is the probability that a randomly selected commuter spends a)between 20 and 30 min commuting one way b)less than 10 min commuting one way

a)0.5875 b)0.0069

the average amount of rain per year in Greenvillle is 49 in. The standard dev. is 8 inches. Find the probiblity that next year Greenville will revieve the following amounts of rainfall. a)at most 55 in. b)at least 62 in. of rain c) between 46 and 54 in.

a)0.7734 b)0.05156 c)0.3737

Find two z values, one positive and one negative, that are equidistant from the mean so that the areas in the two tails total the following values: a)5% b)10% c)1%

a)1.96 b)1.65 c)2.58

A mandatory competency test for high school sophmores has a normal distribution with a mean of 400 and a standard dev of 100: a)the top 2% of students recieve 200$. What is the minimum score you would need to recieve this award? b) the bottom 5% of students must go to summer school. what is the minimum score you would need to stay out of this group?

a)605 b)236