Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 616181: An urn contains 5 red marbles, 8 blue marbles, 7 white marbles, and 5 yellow marbles. 4 marbles are selected at random. What is the probability that each marble is a different color? OR that 4 marbles are the same color?
Click here to see answer by ewatrrr(10682)   |
Question 616184: A confidence interval estimate for the population mean is given to be (42.43, 51.02). If the standard deviation is 17.845 and the sample size is 47, answer each of the following:
(A) Determine the maximum error of the estimate, E.
(B) Determine the confidence level used for the given confidence interval.
Click here to see answer by ewatrrr(10682) |
Question 616225: Bill is doing a project for you in the marketing department. In conducting his analysis regarding consumer behavior and a new product that has come out, he tells you the correlation between these two variables is 1.09. What is your response to this analysis?
Judy has conducted an analysis for her supervisor. The results she obtained was a correlation coefficient that was negative 0.86. Judy is confused by this number and feels that because it is negative and not positive, is means that it is bad. You are here supervisor. How would you clarify this result for Judy regarding the meaning of the correlation?
In a negative correlation, as the values of one of the variables increase, the values of the second variable decrease. Likewise, as the value of one of the variables decreases, the value of the other variable increases. In more familiar terms, it means that one variable is inversely proportional to the second variable.
Click here to see answer by solver91311(17077)  |
Question 616258: If two delegates are randomly chosen to attend a meeting with the President, find the probability that the delegates are of the opposite sex.
This is the information that was given.
Political Party -----Male ------ Female
Democrat--------------4------------5
Republican------------6------------2
Independent-----------2------------1
Click here to see answer by stanbon(57960) |
Question 616256: If two delegates are randomly chosen to attend a meeting with the President, find the probability that the delegates are of the opposite sex.
This is the information given:
Political Party -----Male ------ Female
Democrat--------------4------------5
Republican------------6------------2
Independent-----------2------------1
Click here to see answer by stanbon(57960) |
Question 616248: In a math class, 12 out of 15 girls are fourteen years old and 11 out of 15 boys are fourteen years old. What is the probability of selecting a group of five students - 2 fourteen year old girls and 3 fourteen year old boys? (Explaining the process would be helpful too!)
Click here to see answer by stanbon(57960) |
Question 616224: please help me solve this problem. thank in advance!
A normally distribited population with 200 elements has a mean of 60 and a standard deviation of 10. the probability that the mean of a sample of 25 elements taken from this population will be smaller than 65 is:
A. 0.0166
B. 0.0228
C. 0.3708
D. 0.0394
Click here to see answer by stanbon(57960) |
Question 616221: A government survey conducted to estimate the mean price of houses in a metropolitan area is designed to have a margin of error of $10,000. Pilot studies suggest that the population standard deviation is $70,000. Estimate the minimum sample size needed to estimate the population mean with the stated accuracy.
Click here to see answer by stanbon(57960) |
Question 616203: 3. Your firm’s accountant believes that 15% of the company’s invoices contain arithmetic errors. To check this theory, the accountant randomly selects 50 and checks them.
a) Give the formula for the probability that exactly six of them are in error.
b) Give the mean and standard deviation for distribution representing the number of invoices among the 50 that are in error.
c) Which is larger: the mean or the median? Why?
Click here to see answer by stanbon(57960) |
Question 616220: A sample of nine students is selected from among the students taking a particular exam. The nine students were asked how much time they had spent studying for the exam and the responses (in hours) were as follows:
18, 7, 10, 13 12, 16, 5, 20, 21
Estimate the mean study time of all students taking the exam. Round your answer to the nearest tenth of an hour, if necessary.
Click here to see answer by solver91311(17077) |
Question 616342: I really hope that I have the right place for my questions... if I don't I am really sorry. The name of my lesson is Descriptive statistics. my question is if I have the terms 14, 6, 17 ,15,12, 22, and 19 what term do I add to this sequence to have a mean of 17? I have tried the equation  and I got 36 but that doesn't give me the mean 17. What equation do I use?
Click here to see answer by jim_thompson5910(28705) |
Question 616509: 1. A random sample of 10 women was made to undergo a reducing program for 6 months. Their weights in pounds taken before and after undergoing the program are tabulated below.
Before 164 175 135 165 192 180 175 205 210 208
After 161 170 134 165 188 181 173 195 180 197
Is there a significant decrease in the weights of the women after the program? Test the significance at 0.05 level.
Click here to see answer by ewatrrr(10682) |
Question 616708: I would like to see an example for a question. If light bulbs have lives that are normally distibuted with a mean of 2500 hours and a standard deviation of 500 hours, what percentage of light bulbs have a life less than 2500 hours?
Click here to see answer by stanbon(57960) |
Question 616604: Chicken Delight claims that 84 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 80 orders revealed that 79 percent were delivered within the promised time. At the .10 significance level, can we conclude that less than 84 percent of the orders are delivered in less than 10 minutes?
(b) Compute the value of the test statistic. (Round your answer to 2 decimal places.)
Value of the test statistic
Click here to see answer by stanbon(57960) |
Question 616601: The cost of weddings in the United States has skyrocketed in recent years. As a result many couples are opting to have their weddings in the Caribbean. A Caribbean vacation resort recently advertised in Bride Magazine that the cost of a Caribbean wedding was less than $10,000. Listed below is a total cost in $000 for a sample of 8 Caribbean weddings. At the .05 significance level is it reasonable to conclude the mean wedding cost is less than $10,000 as advertised?
9.7
9.4
11.7
9.0
9.1
10.5
9.1
9.8
(b) State the decision rule for .05 significance level. (Round your answer to 3 decimal places.)
Reject H0 if t <
(c) Compute the value of the test statistic. (Round your answer to 3 decimal places.)
Value of the test statistic
Click here to see answer by stanbon(57960) |
Question 616853: The breaking strength (in pounds) of a certain new synthetic is normally distributed with a mean of 174 and a variance of 9. The material is considered defective if the breaking strength is less than 168 pounds. What is the probability that a single, randomly selected piece of material will be defective. Give the answer to two decimal places. Could someone please explain this to me step by step.
Click here to see answer by ewatrrr(10682) |
Question 616900: the amount of coffee that is dispensed by an automatic machine is normally distributed with a mean of 7 ounces and a standard deviation of 1 ounce. if the machine is used 250 times, about how many of these times would an 8 ounce cup overflow?
(a)40
(b)77
(c)85
(d)210
Click here to see answer by ewatrrr(10682) |
Question 616899: There are 10,000 applicants to the freshmen class at the United States Academy. The class size limit is 1000. If he or she is chosen randomly, what is the probability of a specific applicant being admitted
Click here to see answer by stanbon(57960) |
Question 616852: The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. what is the probabiity that the diameter will exceed 0.815 inch? please show me how to do this one step by step
Click here to see answer by stanbon(57960) |
Question 616887: Hello, I'm having some problems related to test exams and probability. Say you have a test exam composed of N multiple answer questions (I have the probability of guessing each question right or wrong by chance pretty much covered, that's easy). Each question can be either correct (which will add a certain amount of points to the final score), incorrect (which will substract another quantity from the final score) or blank (which will not add nor substract). My question is:
If we know the probability of guessing each question, what is the probability of achieving a certain final score guessing all the test (eg. 5.75)?
Click here to see answer by EdwinParker(16) |
Question 617087: A researcher claims that the average age of people who buy lottery tickets is 65. A sample of 30 is selected and their ages are recorded as shown below. The standard deviation is 6. At a = 0.05 is there enough evidence to reject the researcher’s claim?
49
63
90
52
22
80
72
56
82
56
24
46
70
74
70
61
65
71
39
74
79
76
71
49
62
68
71
67
69
45
Click here to see answer by ewatrrr(10682) |
Question 617081: A study was conducted to estimate the mean amount spent on birthday gifts for a typical family having two children. A sample of 180 was taken, and the mean amount spent was $219.76. Assuming a standard deviation equal to $41.77, find the 99% confidence interval for µ, the mean for all such families.
Click here to see answer by ewatrrr(10682) |
Question 617110: In a poll conducted in 2007, 2000 adults ages 18 and up were asked how frequently they are in touch with their parents by phone. The results of the poll:
monthly 11%, weekly 47%, daily 32%, don't know 2%, less 8%.
If a person who participated in the poll is selected at random, what is the probability that the person said he or she kept in touch with their parents.
a. weekly?
b. At least once a week?
*Any help would be greatly appreciated.
Click here to see answer by stanbon(57960) |
Question 617133: Assume that average annual salary for a worker in th u.s. is $39,000 and the annual annual salary for americans are normally distributed with a standard deviation equal to $7,000 find the following A) what percentage of americans earn below $25,000 B) what percentage of americans earn above $44,000
Click here to see answer by ewatrrr(10682) |
Question 617139: Okay so I'm completely stuck on this problem. How do I go about figuring out whether they are of the probability distribution?
Can you show me a step-by-step?
6. Determine whether each of the distributions given below represents a probability distribution. Justify your answer.
A)
x | 1 2 3 4
------------------------
P(x)| 3/16 3/8 1/4 3/16
B)
x | 3 6 8
----------------------
P(x)| 0.11 21/25 0.06
C)
x | 20 30 40 50
-----------------------------
P(x)| 11/20 0.15 1/5 0.1
Click here to see answer by Edwin McCravy(8999)  |
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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, 21286..21330, 21331..21375, 21376..21420, 21421..21465, 21466..21510, 21511..21555
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