Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 602487: Suppose X is subject to normal distribution with the population mean 7, and the standard deviation 2, what are the lower and upper values of X, located symmetrically around the mean, that will include 95% area under the curve?
Click here to see answer by stanbon(57424)  |
Question 602512: the working women executive magazine reports that 65% of all new female car buyers are women. Assuming that those figures are correct; find the probability that if we select six women at random that four women will be new car buyers
Compute the probability by solving the binomial distribution formula the long way by hand.
Click here to see answer by jim_thompson5910(28598) |
Question 602524: A schoolteacher is concerned that her students watch more TV than the average American child. She reads that according to the American Academy of Pediatrics (AAP), the average American child watches 4 hours of TV per day
(μ = 4.0 hours).
She records the number of hours of TV each of her six students watch per day. The times (in hours) are 5.5, 4.4, 2.8, 2.5, 4.0, and 4.8.
(a) Test the hypothesis that her students watch more TV than the average American child using a 0.05 level of significance and a one-independent sample t-test. State the value of the test statistic. (Round your answer to three decimal places.)
Click here to see answer by stanbon(57424) |
Question 602653: Below are the home states of 19 college professors.
New Jersey Ohio Michigan Georgia Nebraska
Wisconsin Ohio South Carolina Pennsylvania Michigan
Georgia New Jersey Wisconsin Georgia Ohio
Florida Georgia New Jersey South Carolina
i. Make a frequency table using these 9 states:
Florida
Georgia
Michigan
Nebraska
New Jersey
Ohio
Pennsylvania
South Carolina
Wisconsin
My work:
States Tally Frequency
Florida | 1
Georgia |||| 4
Michigan || 2
Nebraska | 1
New Jersey ||| 3
Ohio ||| 3
Pennsylvania | 1
South Carolina || 2
Wisconsin || 2
ii. What is (are) the mode(s)? There are 3 (1s) and 3 (2s)
iii. Does it make sense to talk about the average for this data? Why or why not? Really not sure how to come up with this answer
iv. Using your frequency table draw a pie chart to display the distribution of home states by filling in the following table:
Home State Frequency Percentage of total Measure of Central Angle (in degrees)
Florida
Georgia
Michigan
Nebraska
New Jersey
Ohio
Pennsylvania
South Carolina
Wisconsin
My Work:
Home State Frequency Percentage of total Measure of Central Angle (in degrees)
Florida 1 1/19*100=5.26% .0526*360=18.94 degrees
Georgia 4 4/19*100=21.05% .2105*360=75.78 degrees
Michigan 2 2/19*100=10.53% .1053*360=37.91 degrees
Nebraska 1 1/19*100=5.26% .0526*360=18.94 degrees
New Jersey 3 3/19*100=15.79% .1579*360=56.84 degrees
Ohio 3 3/19*100=15.79% .1579*360=56.84 degrees
Pennsylvania 1 1/19*100=5.26% .0526*360=18.94 degrees
South Carolina 2 2/19*100=10.53% .1053*360=37.91 degrees
Wisconsin 2 2/19*100=10.53% .1053*360=37.91 degrees
Anyone know if this is correct? And can someone tell me how to figure out part iii.?
Click here to see answer by solver91311(16897)  |
Question 559566: Assuming a normal die with six sides, we will define Event A: you roll the die and it’s even. We will define Event B: you roll the die and it is less than 5. Calculate the probabilities for the next 2 questions.
6) Roll the dice once. What is the probability that Event A will occur given that Event B has already occurred?
7) Roll the dice once. What is the probability that Event B will occur given that Event A has already occurred?
Click here to see answer by nathan1234(1) |
Question 274226: The Cincinnati Enquirer, in its Sunday business supplement, reported that the mean number of hours worked per week by those employed full time is 43.9. The article further indicated that about one-third of those employed full time work less than 40 hours per week.
(a)
Given this information and assuming that number of hours worked follows the normal distribution, what is the standard deviation of the number of hours worked?
(b-1)
The article also indicated that 20 percent of those working full time work more than 49 hours per week. Determine the standard deviation with this information.
(b-2) Are the two estimates of the standard deviation similar?
Click here to see answer by sojazzy80(1) |
Question 602841: Generate a frequency distribution of the data for both using Microsoft® Excel
Explain How the frequency distribution might be used to better understand and improve the inventory system
For Lam Research Corporation
Currency and currency equals, short-range savings and limited currency and savings balance remained $2.6 billion at the conclusion of the March 2012 quarterly records, connected to $2.4 billion at the conclusion of the December 2011 quarterly records. The increase in currency and currency equals, short-range savings and limited currency and savings balances throughout the quarter primarily on the account of functioning events and the currency payment of a share repo arrangement that did not execute. Cash flows from functioning events were about $146.4 million through the March 2012 quarterly report. Delayed returns and delayed revenue net at the completion of the March 2012 quarterly report increased to $246.2 million and $139.6 million, consistently. Lam Research postponed returns net exclude deliveries to Japanese clienteles, where name does not transfer pending client approval. Deliveries to Japanese clienteles are categorized as inventory at cost pending the time of approval. The predictable forthcoming return from deliveries to Japanese clienteles was nearly $18.5 million as of March 25, 2012.
Future Inventory Costs
Source: S&P Capital IQ. Data is current as of latest fully reported quarter. Dollar amounts in millions. FY = fiscal year. TTM = trailing 12 months
Source: S&P Capital IQ. Data is current as of latest fully reported quarter. Dollar amounts in millions. FQ = fiscal quarter
Trailing 12-month revenue decreased 6.0%, and inventory increased 11.8%. Over the sequential quarterly period, the trend looks disappointing. Revenue dropped 14.2%, and inventory dropped 5.8%.
On a trailing 12-month basis, raw materials inventory was the fastest growing segment, up 26.4%. On a sequential quarter basis, raw materials inventory was also the fastest-growing segment; up 2.1%. Although Lam Research shows inventory growth that outpaces revenue growth, the company may also display positive inventory divergence, suggesting that management sees increased demand on the horizon.
Click here to see answer by babaea123(2) |
Question 603049: A box of 140 marbles contains only red, green, and blue marbles. There are three times as many green marbles as red marbles. There are six times times as many blue marbles as red marbles. How many blue marbles are there in the box?
Click here to see answer by stanbon(57424) |
Question 603043: In San Francisco, 30% of workers take public transportation daily. Consider a random sample of 10 workers.
Find the probability that at least 3 workers take public transportation daily.
Find the probability that fewer than 2 workers take public transportation daily.
Find the probability that more than 6 workers take public transportation daily.
find the probability that at most 2 workers take public transportation daily.
Click here to see answer by stanbon(57424) |
Question 481027: Popular TV Shows Let U = {60 Minutes, American Idol–Tues., American Idol–Wed., CSI, CSI: Miami, Desperate Housewives, Friends, Grey’s Anatomy, Law & Order, The Apprentice}. Sets A, B, and C that follow show the five most watched television shows for the years 2004, 2005, and 2006, respectively (according to Nielsen Media Research). Then
A = {CSI, American Idol–Tues., American Idol–Wed., Friends, The Apprentice}
B = {CSI, American Idol–Tues., American Idol–Wed., Desperate Housewives, CSI: Miami}
C = {American Idol–Tues., American Idol–Wed., CSI, Desperate Housewives, Grey’s Anatomy}
Construct a Venn diagram illustrating the sets.
Click here to see answer by katielreed(1) |
Question 603128: bill has 25 red tiles, 10 green tiles, and 15 blue tiles. he selects a tile at random, returns it, and selects a second tile. what is the probability that the first tile is blue and the second tile is green?
Click here to see answer by stanbon(57424) |
Question 603313: suppose a person rolls a die 5 times and gets a 5 every single time. Suppose the die is rolled a sixth time, what is the probability that another 5 comes up?
I figured the sixth die would be 1 out of 6. The answer seems too easy. I'm horrible in math so when an answer seems too easy, usually it's wrong.
Click here to see answer by bucky(2189) |
Question 603313: suppose a person rolls a die 5 times and gets a 5 every single time. Suppose the die is rolled a sixth time, what is the probability that another 5 comes up?
I figured the sixth die would be 1 out of 6. The answer seems too easy. I'm horrible in math so when an answer seems too easy, usually it's wrong.
Click here to see answer by scott8148(6628)  |
Question 603457: A company takes a sample of 20 boxes of cereal from their production line.they believe that of the 20 boxes, four will have too little cereal in them and sixteen willhave the correct amount.the company then randomly selects three of the boxes from the twenty and weighs them.assuming the company is correct about the number of light boxes, find the probability that the three boxes selected will all have the correct amount.
I tried to do the binomial probability equation and I ended up with a large number. Please help.
Click here to see answer by solver91311(16897) |
Question 603690: What is the probability that i will choose a face card given that i chose a heart card ?
What is the probability that a couple has three boys and two girls ?
What is the probability that i will choose a face and a heart card ?
What is the probability that i will choose a face or a heart card ?
What is the probability that a couple has two boys and three girls ?
Click here to see answer by stanbon(57424) |
Question 603932: Tom and Carl start 200 miles apart, running towards each other. Tom runs 5 miles per hour faster than Carl. If they meet after 10 hours, how fast are they running?
A. 10 mph and 15 mph
B. 15 mph and 20 mph
C. 2.5 mph and 7.5 mph
D. 7.5 mph and 12.5 mph
Click here to see answer by ewatrrr(10682)  |
Question 603930: 7. The manager of a clothing store wishes to analyze the relationship between the type of customer and the form of payment made. The following data has been collected for 1010 customers.
Customer Credit Card Check Cash Total
Male 296 104 207 607
Female 188 170 45 403
Total 484 274 252 1010
If a customer is selected at random from this group, find the following probabilities. Round your answer to a three place decimal (.123).
a) The customer is a male.
b) The customer paid by credit card.
c) The customer paid by check, given that she is a female.
d) The customer did not pay by credit card.
e) The customer is a male, given that he paid by cash.
f) The customer is a female and she paid by credit card.
g) The customer is a male or the customer paid by cash.
10. Assume that a researcher randomly selected 10 newborn babies and counts the number of girls selected, as x. The probability corresponding to the 10 possible values of x are summarized in the table below. Complete the probability distribution and complete the following questions. Write the mean and standard deviation with a one place decimal and write the probabilities as a three place decimal (.123).
x p(x) x•p(x) x2 •p(x)
0 0.000 0.000 0.000
1 0.001 0.001 0.001
2 0.007 0.014 0.028
3 0.024 0.072 0.216
4 0.062 0.248 0.992
5 0.113 0.565 2.825
6 0.183 1.098 6.588
7 0.209 1.463 10.241
8 0.183 1.464 11.712
9 0.122 1.098 9.882
10 0.096 0.960 9.600
a) Using the formula for the mean of a probability distribution find the average number of baby girls for this distribution.
b) Find the standard deviation.
c) Find the probability of selecting at least 5 girls.
d) Find the probability of selecting at most 7 girls.
e) Use the mean the standard deviation from above and the rule of thumb to find the maximum and minimum number of girls out of the 10 newborn babies. Determine whether a nursery containing 8 baby girls is usual or unusual. Write usual or unusual in the answer text box.
11. A pediatrician finds that about 15% of the infants now injected with the MMR vaccine, as required by law in many states, develop some form of minor reactions. If the doctor intends to inject 400 infants during the year with this vaccine:
a) About how many can be expected (µ=np) to develop any form of a reaction.
b) Find the standard deviation.
c) What is the probability that out of the 400 infants, exactly 25 will develop a reaction? Write your answer as a decimal.
12. If z is a standard normal variable, find the probabilities below. Write your answer as a four place rounded decimal.
a) The probability that z is greater than -1.82.
b) p(-0.73 < z < 2.27)
c) p(z < 2.01)
Question 13
13. Assume that women have heights that are normally distributed with a mean of 63.6 inches and a standard deviation of 2.5 inches. Complete the following, write your answer as a four place rounded decimal (.1234).
a) Find the probability that a randomly chosen woman has a height greater than 60 inches.
b) If 100 women are randomly selected, find the probability that they have a mean height between 63.5 inches and 64.5 inches. Use the central limit theorem.
14. Given the data below, find the mean of the original three samples. List the different possible samples taking two at a time, find the mean of each of them and then find the overall population mean of the 9 samples. How does the sample mean compare with the population?
Personal phone calls received in the last three days by a new employee were 3, 5, and 6. Assume that the samples of size 2 are randomly selected with replacement from this population of three values.
15. A survey of 865 voters in one state reveals that 408 favor approval of an issue before the legislature. Construct the 95% confidence interval for the true proportion of all voters in the state who favor approval. Indicate the following values.
a) p-hat rounded to three decimal places
b) q-hat rounded to three decimal places.
c) margin of error, E =
d) confidence interval: < p <
16. If an additional survey is to be completed, how large of a sample must be taken to be 99% confident that the estimate is within 2% of the true proportion of voters? Round the answer to the nearest whole number. n =
17. A random sample of 94 light bulbs had a mean life of 587 hours with a standard deviation of 36 hours. Construct a 90% confidence interval for the mean life of all light bulbs of this type.
a) Find the margin of error, E= Round to tenths place.
b) Confidence Interval: Round the tenths place. < µ <
18. Use the given degree of confidence and the sample data below to construct a confidence interval for the population mean. Assume that the population is normally distributed and round your answers to one decimal place.
The principal randomly selected six students to take an aptitude test.
There scores were:
83.0 84.1 83.5 83.7 84.1 73.5
Determine a 90% confidence interval for the mean score of the six students.
a) sample mean =
b) standard deviation =
c) margin of error, E =
d) 90% confidence interval: < µ <
19. Assume that a simple random sample has been selected from a normally distributed population. State the null hypothesis, the alternate hypothesis, the test statistic, the p-value, the critical value and state the conclusion.
Test the claim that the mean lifetime of a car engine of a particular type is greater than 220,000 miles. Sample data are summarized as n=23, mean = 226,450 miles, the population standard deviation,
= 11,500 miles. Use a z-test and a significance level of 0.01.
a) Ho: µ < miles.
b) Ha: µ > miles.
c) test statistic z = Round to two decimal places.
d) p-value = Round to four decimal places.
e) Write reject or do not reject the null hypothesis.
f) Conclusion: There is or is not sufficient evidence to show that the lifetime of the car engine is greater than 220,000.
20. Assume that a hypothesis test of the given claim will be conducted. Identify the type I error for the test.
The principal of a middle school claims that test scores of the seventh-graders at his school average less than the test scores of seventh graders at a neighboring school, which has an average described by a mean = 74.7.
Answer
a. The error of failing to reject the claim that the mean is less than 74.7 when it actually is equal to 74.7.
b. The error of rejecting the claim that the mean is less than 74.7 when it actually is equal to 74.7.
c. none of the above
d. The error of rejecting the claim that the mean is less than 74.7 when it is actually is less than 74.7.
Click here to see answer by stanbon(57424) |
Question 604050: In a city 32% of residents are over 50 years of age. Of those residents over 50, 78% have some kind of retirement savings. What percent of the city residents are over 50 years of age and have some kind of retirement savings?
Click here to see answer by flame8855(424)  |
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3871..3915, 3916..3960, 3961..4005, 4006..4050, 4051..4095, 4096..4140, 4141..4185, 4186..4230, 4231..4275, 4276..4320, 4321..4365, 4366..4410, 4411..4455, 4456..4500, 4501..4545, 4546..4590, 4591..4635, 4636..4680, 4681..4725, 4726..4770, 4771..4815, 4816..4860, 4861..4905, 4906..4950, 4951..4995, 4996..5040, 5041..5085, 5086..5130, 5131..5175, 5176..5220, 5221..5265, 5266..5310, 5311..5355, 5356..5400, 5401..5445, 5446..5490, 5491..5535, 5536..5580, 5581..5625, 5626..5670, 5671..5715, 5716..5760, 5761..5805, 5806..5850, 5851..5895, 5896..5940, 5941..5985, 5986..6030, 6031..6075, 6076..6120, 6121..6165, 6166..6210, 6211..6255, 6256..6300, 6301..6345, 6346..6390, 6391..6435, 6436..6480, 6481..6525, 6526..6570, 6571..6615, 6616..6660, 6661..6705, 6706..6750, 6751..6795, 6796..6840, 6841..6885, 6886..6930, 6931..6975, 6976..7020, 7021..7065, 7066..7110, 7111..7155, 7156..7200, 7201..7245, 7246..7290, 7291..7335, 7336..7380, 7381..7425, 7426..7470, 7471..7515, 7516..7560, 7561..7605, 7606..7650, 7651..7695, 7696..7740, 7741..7785, 7786..7830, 7831..7875, 7876..7920, 7921..7965, 7966..8010, 8011..8055, 8056..8100, 8101..8145, 8146..8190, 8191..8235, 8236..8280, 8281..8325, 8326..8370, 8371..8415, 8416..8460, 8461..8505, 8506..8550, 8551..8595, 8596..8640, 8641..8685, 8686..8730, 8731..8775, 8776..8820, 8821..8865, 8866..8910, 8911..8955, 8956..9000, 9001..9045, 9046..9090, 9091..9135, 9136..9180, 9181..9225, 9226..9270, 9271..9315, 9316..9360, 9361..9405, 9406..9450, 9451..9495, 9496..9540, 9541..9585, 9586..9630, 9631..9675, 9676..9720, 9721..9765, 9766..9810, 9811..9855, 9856..9900, 9901..9945, 9946..9990, 9991..10035, 10036..10080, 10081..10125, 10126..10170, 10171..10215, 10216..10260, 10261..10305, 10306..10350, 10351..10395, 10396..10440, 10441..10485, 10486..10530, 10531..10575, 10576..10620, 10621..10665, 10666..10710, 10711..10755, 10756..10800, 10801..10845, 10846..10890, 10891..10935, 10936..10980, 10981..11025, 11026..11070, 11071..11115, 11116..11160, 11161..11205, 11206..11250, 11251..11295, 11296..11340, 11341..11385, 11386..11430, 11431..11475, 11476..11520, 11521..11565, 11566..11610, 11611..11655, 11656..11700, 11701..11745, 11746..11790, 11791..11835, 11836..11880, 11881..11925, 11926..11970, 11971..12015, 12016..12060, 12061..12105, 12106..12150, 12151..12195, 12196..12240, 12241..12285, 12286..12330, 12331..12375, 12376..12420, 12421..12465, 12466..12510, 12511..12555, 12556..12600, 12601..12645, 12646..12690, 12691..12735, 12736..12780, 12781..12825, 12826..12870, 12871..12915, 12916..12960, 12961..13005, 13006..13050, 13051..13095, 13096..13140, 13141..13185, 13186..13230, 13231..13275, 13276..13320, 13321..13365, 13366..13410, 13411..13455, 13456..13500, 13501..13545, 13546..13590, 13591..13635, 13636..13680, 13681..13725, 13726..13770, 13771..13815, 13816..13860, 13861..13905, 13906..13950, 13951..13995, 13996..14040, 14041..14085, 14086..14130, 14131..14175, 14176..14220, 14221..14265, 14266..14310, 14311..14355, 14356..14400, 14401..14445, 14446..14490, 14491..14535, 14536..14580, 14581..14625, 14626..14670, 14671..14715, 14716..14760, 14761..14805, 14806..14850, 14851..14895, 14896..14940, 14941..14985, 14986..15030, 15031..15075, 15076..15120, 15121..15165, 15166..15210, 15211..15255, 15256..15300, 15301..15345, 15346..15390, 15391..15435, 15436..15480, 15481..15525, 15526..15570, 15571..15615, 15616..15660, 15661..15705, 15706..15750, 15751..15795, 15796..15840, 15841..15885, 15886..15930, 15931..15975, 15976..16020, 16021..16065, 16066..16110, 16111..16155, 16156..16200, 16201..16245, 16246..16290, 16291..16335, 16336..16380, 16381..16425, 16426..16470, 16471..16515, 16516..16560, 16561..16605, 16606..16650, 16651..16695, 16696..16740, 16741..16785, 16786..16830, 16831..16875, 16876..16920, 16921..16965, 16966..17010, 17011..17055, 17056..17100, 17101..17145, 17146..17190, 17191..17235, 17236..17280, 17281..17325, 17326..17370, 17371..17415, 17416..17460, 17461..17505, 17506..17550, 17551..17595, 17596..17640, 17641..17685, 17686..17730, 17731..17775, 17776..17820, 17821..17865, 17866..17910, 17911..17955, 17956..18000, 18001..18045, 18046..18090, 18091..18135, 18136..18180, 18181..18225, 18226..18270, 18271..18315, 18316..18360, 18361..18405, 18406..18450, 18451..18495, 18496..18540, 18541..18585, 18586..18630, 18631..18675, 18676..18720, 18721..18765, 18766..18810, 18811..18855, 18856..18900, 18901..18945, 18946..18990, 18991..19035, 19036..19080, 19081..19125, 19126..19170, 19171..19215, 19216..19260, 19261..19305, 19306..19350, 19351..19395, 19396..19440, 19441..19485, 19486..19530, 19531..19575, 19576..19620, 19621..19665, 19666..19710, 19711..19755, 19756..19800, 19801..19845, 19846..19890, 19891..19935, 19936..19980, 19981..20025, 20026..20070, 20071..20115, 20116..20160, 20161..20205, 20206..20250, 20251..20295, 20296..20340, 20341..20385, 20386..20430, 20431..20475, 20476..20520, 20521..20565, 20566..20610, 20611..20655, 20656..20700, 20701..20745, 20746..20790, 20791..20835, 20836..20880, 20881..20925, 20926..20970, 20971..21015, 21016..21060, 21061..21105, 21106..21150, 21151..21195, 21196..21240, 21241..21285
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