Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 360553: A survey-taker asks the age of each person in a random sample of 20 people. X is the age for the individuals.
Does X have a binomial distribution?
A. Yes.
B. No, because the observations are not all independent.
C. No, because there are more than two possible outcomes for each observation.
D. No, because there is not a fixed number of observations.
Click here to see answer by edjones(7569)   |
Question 360552: Suppose 60% of all people who are eligible for jury duty in a large Florida city are in favor of capital punishment. A jury of 12 is to be randomly selected from among all the prospective jurors in this city. Let X be the number of jurors in the jury who are in favor of capital punishment.
a) Does X have a binomial distribution? Explain.
b) What is the probability that 10 of the 12 jury members are in favor of capital punishment?
c) Find the mean of the distribution and explain what that number means in this context.
Click here to see answer by edjones(7569) |
Question 360434: Suppose 60% of all people who are eligible for jury duty in a large Florida city are in favor of capital punishment. A jury of 12 is to be randomly selected among all the prospective jurors in this city. Let X be the number of jurors inthe jury who are in favor of capital punishment. A) Does X have a binomial Distribution? Explain. B) What is the probability that 10 of the 12 jury members are in favor of capital punishment? C) Find the mean of the distribution and explain what the number means in this context.
Click here to see answer by robertb(4012)  |
Question 360435: The first national bank of wilson has 650 (population) checking account customers. A recenter sample of 50 (sample) of these customers showed 26 to have a visa card with the bank. Construct the 99 percent confidence interval for the proportion of checking account customers who have a visa card with the bank.
Click here to see answer by robertb(4012) |
Question 360460: The federal government recently granted funds for a special program designed to reduce crime in high-crime areas. A study of the results of the program in eight high-crime areas of Miami, Florida, yielded the following results.
Number of Crimes by Area
A B C D E F G H
before 14 7 4 5 17 12 8 9
after 2 7 3 6 8 13 3 5
Has there been a decrease in the number of crimes since the inauguration of the program? Use the .01 significance level. Estimate the p-value.
Click here to see answer by robertb(4012) |
Question 360417: From surveys we know that 45% of dentists use nitrous oxide (laughing gas) in their practice. If we select many random samples of 10 dentists, on average how many of them would you expect to use laughing gas in their practice? A. 5. B. 4.5. C. Impossible to tell. D. 2
Click here to see answer by robertb(4012) |
Question 360511: The probability of contracting the kissing disease is .23 when one is exposed to a certain provocative environment. 60 people are exposed. What is the probability that no more than 10 are infected with this dreaded disease.
Click here to see answer by robertb(4012) |
Question 360451: The federal government recently granted funds for a special program designed to reduce crime in high-crime areas. A study of the results of the program in eight high-crime areas of Miami, Florida, yielded the following results.
Area A B C D E F G H
before 14 7 4 5 17 12 8 9
after 2 7 3 6 8 13 3 5
Has there been a decrease in the number of crimes since the inauguration of the program? Use the .01 significance level. Estimate the p-value.
Click here to see answer by robertb(4012) |
Question 360671: Americans watch an average of 4.0 hours of television per day with a standard deviation of 2.1 hours per day. Let's say we would pick many, many random samples of 100 Americans, and find the mean number of hours watched for each sample. These sample means would create a sampling distribution for the sample mean. According to the Central Limit Theorem, what would be the shape, the mean, and the standard deviation of this sampling distribution?
A. The shape would be approximately normal because n > 30. The mean would be 4.0 hours, and the standard deviation would be 0.21 hours.
B. The shape would be approximately normal because n > 30. The mean would be 4.0 hours, and the standard deviation would be 2.1 hours.
C. The shape would be exactly normal because n > 30. The mean would be 4.0 hours, and the standard deviation would be 0.21 hours.
D. The shape would be approximately normal because n > 30. The mean would be 0.4 hours, and the standard deviation would be 0.21 hours.
Click here to see answer by stanbon(57214) |
Question 360680: The sum of the heights of all the students in a class is 1,472 in. The mean height is 5ft-4in. How many students are in the class?
I came up with 23. I changed the 5ft to 60 inches and added 4. Then I took 1472 divided it by 64 = 23 students. If I am correct the next question is:
The median height is 5ft 2in. How many students are 5ft 2 in or taller? I don't know how to get this answer.. Then the last questions is how many students are shorter then 5ft 2in.
Click here to see answer by ewatrrr(10682)  |
Question 360765: If heights of individual women are expressed in units of centimeters, what are the units used for the z-scores that correspond to individual heights?
A. centimeters
B. It depends on the units of the mean and standard deviation.
C. z-scores have no units.
Click here to see answer by jim_thompson5910(28476) |
Question 360765: If heights of individual women are expressed in units of centimeters, what are the units used for the z-scores that correspond to individual heights?
A. centimeters
B. It depends on the units of the mean and standard deviation.
C. z-scores have no units.
Click here to see answer by stanbon(57214) |
Question 360771: Please help me with this homework problem.
8) What is the probability a co-worker is absent given that it is Friday if the probability that it is Friday and that a co-worker is absent is 0.01. Because there are 5 work days in a week, the probability that it is Friday is 0.2.
Click here to see answer by jim_thompson5910(28476) |
Question 360768: The average monthly mortgage payment for recent home buyers in certain city is μ = $732, with standard deviation of σ = $421 A random sample of 125 recent home buyers is selected. The approximate probability that their average monthly mortgage payment will be more than $782 is:
A. 0.3822
B. 0.0918
C. 0.1976
D. 0.4556
Click here to see answer by stanbon(57214) |
Question 360778: Please help me with this homework assignment. I have submitted it three times and continue to get it wrong.
9) At CSN the probability that a student takes Introduction to Statistics and Introduction to Economics is 0.29. The probability that a student takes Statistics is 0.53. What is the probability that a student takes Economics given that the student is taking Statistics?
This is what I submitted:
P(IS+IE)= 0.29 or 29%
P(IS)= 0.53 or 53%
P(IS)- P(IS+IE)= (53-29)= 24% or P(ISIE)= 0.24
Click here to see answer by stanbon(57214) |
Question 360789: Please help me with this homework assignment. I have submitted it three times and continue to get it wrong.
7) In Summerville there are 1000 people and 600 of them are female. Also, 200 people are red haired, out of which 150 are female. If a person was randomly picked from Summerville, find the probability of picking either a female or red head.
I have submitted this:
600/1000 = female or a 60% chance of picking a female
150/1000= female redhead 15% chance
200/1000= 20% of picking redhead
Click here to see answer by ewatrrr(10682) |
Question 360791: Please help me with my probability homework! It has been sent back to me twice and my book is no help.
5) In Summerville scientists have noticed that there is 24% chance of sun on any day, a 17% chance of snow, a 15% chance of rain, and 21% of fog. What is the probability that tomorrow in Summerville will either be sunny, foggy or rainy?
I have submitted:
Sunny= 24% or 6/25
P(Sunny)= 0.24
Foggy= 21% or 21/100
P(Foggy)= 0.21
Rain= 15% or 3/20
P(rain)= 0.15
S+F+R= 60% or 3/5
P(Sunny + Foggy + Rain)= P(0.24+0.21+0.15)= 0.60
There is a three in five chance it will either be sunny, foggy, or rainy in Summerville tomorrow. That is a sixty percent chance for the above conditions.
Click here to see answer by edjones(7569) |
Question 360881: A manufacturer of computer printers purchases plastic ink cartridges from a vendor. When a large shipment is received, a random sample of 208 cartridges is selected, and each cartridge is inspected. If the sample proportion of defective cartridges is more than .02, the entire shipment is returned to the vendor.
(a) What is the approximate probability that a shipment will be returned if the true proportion of defective cartridges in the shipment is 0.07? (Round the answers to three decimal places.)
P =
Click here to see answer by edjones(7569) |
Question 360860: Please help me with this problem ASAP!
10) What is the probability that a CSN political science student completes a 4-year degree and then attends law school, and then passes the Bar exam on the first try? There is a 50% chance that a CSN Political Science student will finish a 4-year degree, and 5% chance that once the 4-year degree is completed the student will attend law school, and a 20% of passing the Bar exam on the first attempt after going through all of that.
I have worked it multiple times and keep getting it wrong. I have submitted:
P(4yr)= 50%
P(lawschool)= 5%
P(bar)= 20%
50%-5%-20%= 25%
(.5)(.05)(.2)= .005= 0.5%
Click here to see answer by edjones(7569) |
Question 360983: --------------- QUESTION FOLLOWS --------------------------
How many green elements ae required to make this a legitimate probability distrubtion if there are a total of 50 elements in this sample?
X
red
blue
orange
brown
green
P(x)
0.10
0.10
0.18
0.22
Click here to see answer by Fombitz(13828)  |
Question 361101: A box contains three red balls, five black balls, and
four white balls. Suppose one ball is drawn at random.
Find the probability of each of the following
events:
a. A black ball is drawn.
b. A black or a white ball is drawn.
c. Neither a red nor a white ball is drawn.
d. A red ball is not drawn.
e. A black ball and a white ball are drawn.
f. A black or white or red ball is drawn.
Click here to see answer by edjones(7569) |
Question 361095: In testing a new drug, researchers found that 1% of all patients using it will have a mild side effect. A random sample of 15 patients using the drug is selected. Find th eprobability that:
A.) exactly one will have this mild side effect.
B.) at least one will have this mild side effect.
Click here to see answer by edjones(7569) |
Question 361076: A batch of 350 raffle tickets contains four winning tickets. You buy four tickets. What is the probability that you have
a.) no winning tickets?
b.) all of the winning tickets?
c.) at least one winning ticket?
d.) at least one non-winning ticket?
Click here to see answer by edjones(7569) |
Question 361118: On a certain street are three traffic lights. At any
given time, the probability that a light is green is
0.3. What is the probability that a person will hit all
three lights when they are green if they represent
independent events?
Click here to see answer by edjones(7569) |
Question 361195: Assume that the average annual salary for a worker in the United States is $37,500 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $7,000. Find the following:
(A) What percentage of Americans earn below $27,000?
(B) What percentage of Americans earn above $45,000?
Please show all of your work.
Click here to see answer by stanbon(57214) |
Question 361312: I'm working on my statistics homework and need help with a few questions.
This is the information provided:
Define two events:
A = the person chosen is obese
B = the person chosen is overweight, but not obese
According to the National Center for Health Statistics
P(A) = 0.32 and P(B) = 0.34
1.Say in plain language what the event “A or B” is.
2. If C is the event that the person chosen has normal weight or less, what is P(C)?
For question #1 I submitted:
Probability of Disjoint Events
P(A or B) = P(A) + P(B)
.32 + .34= .66
dependent events:
P(either A or B happens) = P(A happens) + P(B happens)
For question #2 I submitted:
1 – .66 = .34
P(C)= .34
Is this correct? Please help!
Click here to see answer by stanbon(57214) |
Question 361410: In a class of 50 students, 31 are democrats, 13 are business majors, and 3 of the business majors are democrats. If one student is randomly selected from the class, find the probability of choosing a Democrat or business major.
Click here to see answer by neatmath(300)  |
Question 361579: A class of 13 students is trying to decide how they should form themselves into groups of 4 for an upcomiing classroom activity. One of the students first proposes they calculate how many combinations of 4 students can be made from 13 people. After doing the calculations, how many groups of 4 people can be made from a student population of 13 people?
Click here to see answer by stanbon(57214) |
Question 361581: 1. –/2 points Notes
Problem 7-22 A food-packaging apparatus underfills 20% of the containers. Find the probability that for any particular 10 containers the number of underfilled will be:
Note: This question uses a tolerance of .0001 for grading. Make sure your answers are entered to the fifth decimal place.
Example: .00123
(a) exactly 2
Pr=
(b) exactly 5
Pr=
(c) exactly 8
Pr=
(d) at least 3
Pr=
2. –/2 points Notes
Problem 7-24 Suppose that 30% of the applicants to an engineering school are women. An admissions committee reviews applications in groups of 100. Find the probability that the number of women in the next group is:
Note: This question uses a tolerance of .0001 for grading. Make sure your answers are entered to the fifth decimal place.
Example: .00123
(a) less than or equal to 21
Pr=
(b) between 25 and 40 inclusively
Pr=
(c) greater than 30
Pr=
(d) less than 7
Pr=
(e) exactly 30
Pr=
(f) greater than 54
Pr=
3. 0/2 points All Submissions Notes
Problem 7-28 A student selects his answers on a true/false examination by tossing a coin (so that any particular answer has a .50 probability of being correct). He must answer at least 70% correctly in order to pass. Find his probability of passing when the number of questions is
(a) 10
Pr=210
(b) 20
Pr=
(c) 50
Pr=
(d) 100
Pr=
4. –/2 points Notes
7.30 A quality-control inspector rejects any shipment of printed circuit boards whenever 3 or more defectives are found in a sample of 20 boards tested. Find the (1) expected number defective and (2) the probability of rejecting the shipment when the proportion of defectives in the entire shipment is
(a) Proportion of Defectives=0.01
Expected Number Defective=
Probability of Rejecting the Shipment=
(b) Proportion of Defectives=0.05
Expected Number Defective=
Probability of Rejecting the Shipment=
(c) Proportion of Defectives=0.1
Expected Number Defective=
Probability of Rejecting the Shipment=
5. –/2 points Notes
Problem 7-32 An engineer has designed a modified welding robot. The robot will be considered good enough to manufacture if it misses only 1% of its assigned welds. And it will be judged a poor performer if it misses 5% of its welds. (In-between possibilities are not considered.) A test is performed involving 100 welds. The new design will be accepted if the number of missed welds R is 2 or fewer and rejected otherwise.
(a) What is the probability that a good design will be rejected?
Probability=
(b) What is the probability that a poor design will be accepted?
Probability=
Click here to see answer by solver91311(16868)  |
Question 361498: Suppose that 51% of the women who gave birth at a certain hospital last year were over years 30 old, and that 51% were unmarried. If 61% of the women were over30 or unmarried (or both), what is the probability that a woman who gave birth at the hospital was both unmarried and over 30 ?
Click here to see answer by stanbon(57214) |
Question 361608: The final exam scores of students taking a biology course at a university are normally distributed with a population mean of 73 and population standard deviation of 15. Nine students are randomly selected from the university and let x be their average score.
What is the probability that their average biology score x is between 60 and 80?
Here's what I have so far...
z=(60-73)/5, z=(80-73)/5
z=-2.6;1.4
P(-2.6 < x < 1.4)
P(z<1.4)-P(z<-2.6)
Click here to see answer by stanbon(57214) |
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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, 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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, 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