Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 212074: I have six grandchildren, the youngest born on August 10, 2009. My oldest grandchild was born on August 10, 1996 and her younger sister was born on August 10, 2000. What is the probability of having 3 of 6 grandchildren share the same birthday?
Jack Frost, MD
Click here to see answer by stanbon(57361)  |
Question 212199: I have discussion question that I cannot figure out how to do! Can anybody help me?!?! Thank you!
The questoin reads as follows:
The following statistics provide information about the scores on a national History exam.
Mean 540 First Quartile 260
Median 450 Third Quartile 678
Mode 468 90th Percentile 890
a) What score did half of the test takers surpass?
b) What was the most common score?
c) What percentage of the test takers scored 678 or better?
d) If Joe had a score of 890, explain the meaning of his score.
Click here to see answer by rfer(12662) |
Question 212201: I have a discussion question that I cannot find how to even go about doing this problem. Anyone have any ideas? Thanks!
The question reads as follows:
In a study of 100 married women with children, the subjects were asked the major reason for working outside the home. The study resulted in the following data:
Reason Number of Responses
To support self/family 65
For extra money 20
For something different to do 10
Other 5
----------------------------------------------------------------
Total 100
Construct a pie chart for the data and analyze the results.
Click here to see answer by stanbon(57361) |
Question 212403: One examiner has a pile of 20 CVs to analyze and one coin. If he gets heads then he moves on to the next CV in line (ex: if on the 1st toss he gets heads then he moves on to CV no. 2). Otherwise if he gets tails then he moves on to the previous CV (ex: if on the 1st toss he gets tails then he moves on to CV no. 20). Knowing that your CV is no. 15 then what is the probability of being on your CV on the 40th toss?
Click here to see answer by Theo(3464)  |
Question 212461: Please help with this solution almost done
The objective of statistics is best described as
A)To make inferences about a sample based on information we get form a population.
B)To make inferences about a population based on information we set from a sample taken from the population.
C)To use population mean,(upside down backward u symbol) as an estimate of the sample mean, (x with a small slash on top of it).
D)To make inferences about a sample with a high degree of reliability
Click here to see answer by stanbon(57361) |
Question 212445: Help! need the solution to this wil appreciate this
In a study of 100 married women with children, the subjects were asked the major reason for working outside the home. The study resulted in the following data:
Reason-----------------------------Number of Responses
To support self/family--------------------65
For extra money---------------------------20
For something different to do-------------10
Other--------------------------------------5
Total------------------------------------100
Construct a pie chart for the data and analyze the results.
Click here to see answer by stanbon(57361) |
Question 212459: Can I get some help with this one thanks
Find the mean, median, and mode for the following set of data which shows the number of pages per article in a random sample of magazine articles.
6---7---5---4---7---5---5---7
8---5---3---6---8---9---5
Click here to see answer by stanbon(57361) |
Question 212438: Please help with this question.
State True or False
a) A collection of all the objects to be studied is a population.
b) A subset or part of the population is called a partial population.
c) In a frequency distribution, the class size is always 4.
d) The sum of the percents of the sectors in a pie chart should be 100%.
e) A frequency distribution can be illustrated using a histogram.
Click here to see answer by stanbon(57361) |
Question 212782: Growth of bacteria. The bacteria Escherichia coli (E. coli) are commonly found in the human bladder. Suppose that 3000 of the bacteria are present at time t=0. Then t minutes later, the number of bacteria present is N(t) = 3000(2)^t/20. if 100,000 bacteria accumulate, a bladder infection can occur. If, at 11:00am, a patient's bladder contains 25,000 E. coli bacteria, at what time can infection occur?
Click here to see answer by stanbon(57361) |
Question 212987: Information from the American Institute of Insurance indicates the mean amount of the insurance per household in the United States is $110,000. This distribution follows the normal distribution with a standard deviation of $40,000.
If we select a random sample of 50 households, what is the standard error of mean?
What is the expected shape of the distribution of the sample mean?
What is the likelihood of selecting a sample with a mean of at least $112,000?
What is the likelihood of selecting a sample with a mean of more than $100,000?
Find the likelihood of selecting a sample with a mean of more than $100,000 but less than $112,000?
Click here to see answer by stanbon(57361) |
Question 212790: HELP! I can't figure this one out please help my grade depends on this one a solution is appreciated. Thanks
Construct a grouped frequency distribution of the ages that 30 randomly selected smokers started smoking:
25---26---25---17---16---16---14---17---21---16
15---18---17---15---15---19---16---17---23---15
19---17---16---26---16---25---16---17---22---24
Click here to see answer by rfer(12662) |
Question 212791: Need Some devine intervention with this one Thanks so much
Three-fourths of the numbers in any data set will be larger than the
A)first quartile, B)third quartile, C)median, D)midrange, E)fourth quartile
Click here to see answer by rfer(12662) |
Question 213082: sherry spent the amount of money at the grocery store as she did at drug store. At the grocery store , she spent $3.40 on steak , $1.19 on bread and bought apples that cost $0.15 each. at the drug store , she spent $4.99 on shampoo and bought pencils that cost $0.10 each. how many pencils and how many apples did sherry buy?
Click here to see answer by RAY100(1637) |
Question 213457: A committee of three is selected at random from a set consisting of five Democrats, eight Republicans, and two Independents
What is the probability that the committee consists of all Democrats?
What is the probability that the committee consists of no Republicans
Click here to see answer by stanbon(57361) |
Question 213459: A random sample of 100 students at Southern University was collected. The mean age was found to be 24.2 years, with a standard deviation of 3.4 years.
(a) What percentage of students are over 27.6 years old? 4%
(b) What percentage of the students are between 20.8 and 24.2 years old? 9%
(c) If a student is selected at random from Southern University, what is the probability that he or she will be over 20.8 years old? 5%
Ignore the 4 percent, 9 percent and the 5 percent that was what I think the answer is.
Click here to see answer by stanbon(57361) |
Question 213506: In a particular suburb, 30% of the households have installed electronic security systems.
a. If a household is chosen at random from this suburb, what is the probability that this household has not installed an electronic security system?
b. If two households are chosen at random from this suburb, what is the probability that neither has installed an electronic security system?
Click here to see answer by stanbon(57361) |
Question 211774: A study regarding the relationship between age and the amount of pressure sales personnel
feel in relation to their jobs revealed the following sample information. At the .01 significance
level, is there a relationship between job pressure and age?
Age (years) Low Medium High
Less than 25 20 18 22
25 up to 40 50 46 44
40 up to 60 58 63 59
60 and older 34 43 43
Totals 162 170 168
Click here to see answer by stanbon(57361) |
Question 211773: For many years TV executives used the guideline that 30 percent of the audience were
watching each of the prime-time networks and 10 percent were watching cable stations on
a weekday night. A random sample of 500 viewers in the Tampa–St. Petersburg, Florida,
area last Monday night showed that 165 homes were tuned in to the ABC affiliate, 140 to
the CBS affiliate, 125 to the NBC affiliate, and the remainder were viewing a cable station.
At the .05 significance level, can we conclude that the guideline is still reasonable?
Click here to see answer by stanbon(57361) |
Question 213906: 1. You become suspicious when a genetics researcher selects groups of 20 newborn babies and seems to consistently get 10 girls and 10 boys. The researcher explains that it is common to get 10 boys and 10 girls in such cases.
(a) If 20 newborn babies are randomly selected, how many different gender sequences are possible?
(b) How many different ways can 10 boys and 10 girls be arranged in a sequence?
(c) What is the probability of getting 10 girls and 10 boys when 20 babies are born?
(d) Based on the preceding results, do you agree with the researcher’s explanation that it is common to get 10 boys and 10 girls when 20 babies are randomly selected?
2. Assume that you alarm clock has a 0.975 probability of working on any given morning. Determine the probability that
(a) your alarm clock will not work on the morning of an important final exam
(b) if you had two such alarm clocks, they both would fail on the morning of an important final exam
(c) you would be awakened by the alarm if you had two such clocks.
3. Singing legend Frank Sinatra recorded 381 songs. From a list of his top ten songs, 3 are to be selected as a medley tribute at the next music awards. Determine the number of different medleys possible.
4. Use a simulation of 20 families to estimate the probability of having at least 3 girls in a family of 5.
Click here to see answer by stanbon(57361) |
Question 213946: Mrs. camillo gave 7 points of extra credit to her 7th-grade math class on their last test. If Michael's score on the test was 48 out of 50 before the extra credit was given, what is his percentage on the exam after the extra credit was given?
Click here to see answer by rfer(12662) |
Question 213853: The probability is 1 in 4,000,000 that a single auto trip in the United States will result in a fatality. Over a lifetime, an average U.S. driver takes 50,000 trips. (a) What is the probability of a fatal accident over a lifetime? Explain your reasoning carefully. Why might the assumption of indepenent be violated? (b) Why might a driver be tempted not to use a seat belt "just on this trip".
Click here to see answer by stanbon(57361) |
Question 213797: (2)Mrs.smith reading class can read a mean of 175 words per minute with a standared deviation of 20 words per minute. The top 3% of the class is to receive a special award. What is the minimum number of words per minute a student would have to read in order to get the award?
Click here to see answer by stanbon(57361) |
Question 213767: The depot is using a standard of 635 hours for a particular modification effort. You are to review the standard and determine whether it should be revised. After sampling 20 of these modifications you calculate a mean of 665 hours and a standard deviation of 45 hours. We are concerned that the hours might be higher or lower than the 635 hour standard. Test the standard at the .10 level of significance. Select the correct answer out of each pair of choices. (Carry intermediate calculations to three decimal places.)
1. The tp is 1.328
1. The tp is 1.729
2. The tc is 2.981
2. The tc is 13.333
3. We would reject the null hypothesis
3. We would fail to reject the null hypothesis
4. We would recommend using the existing standard
4. We would recommend revising the standard
Click here to see answer by stanbon(57361) |
Question 213766: Nine software engineers were interviewed to develop an estimate for software lines of code. The mean estimate is 12480 lines of code with a standard deviation of 2400 lines of code. Develop an 80% confidence interval for the population mean. (Carry intermediate calculations to three decimal places.)
Click here to see answer by stanbon(57361) |
Question 214372: Please show work on how you solved confidence interval problem. A sample of 20 pages was taken withreplacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block ofmulticolored illustrations, maps, and text). The data (in sqaure milltimeters) are shown.
0 260 356 403 536 0 268 369 428 536
268 396 469 536 162 338 403 536 536 130
a. Construct a 95 percent confidence innterval for the true mean. b. Why might normality be an issue here? c. What sample size would be needed to obtanin an error of =+ 10 square millimeters with 99 percent confidence? d. If this is not a reasonble suggest one that is
Click here to see answer by stanbon(57361) |
Question 214666: Ignoring twins and other multiple births, assume babies born at a hospital are independent events with the probability that a baby is a boy is 0.5. Find the probability that the next three babies will be all boys?
Click here to see answer by stanbon(57361) |
Question 214683: if a jar contains 23 red marbles and 4 green marbles, the probability that a marble selectted from the jar at random will be green is?
If the above green is not replaced, what is the probability that the next pulled marbles is red?
if you reached into the jar 4 times, what is the probability that you would never choose a green marble (after each pullout you do not replace the chosen marble?
Click here to see answer by jim_thompson5910(28595) |
Question 214663: 1. For a normally distributed population with m = 200, standard deviation of 10 what is the probability of picking one member of the population at random and have it fall:
a. Between 180.40 and 219.6?
b. Above 219.6?
c. Below 180.4?
2. Scores on a standardize test have a mean of 150 and a standard deviation of 15. You are told your score is in the top 1% of the people who took the test. What score defines the top 1% of all scores?
3. A sample of 144 results in a sample mean of 14 and a sample standard deviation of 24. What is the 95% confidence interval on the population mean? What information does the confidence interval give?
Click here to see answer by stanbon(57361) |
Question 214730: The following probabilities are given for two events A and B: P(A)=1/4, P(B)=1/3, P(A|B)=1/2. Find P(A or B).
Could you show me how you arrived at solution so I can understand the process. Thank you for helping.
Click here to see answer by stanbon(57361) |
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Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585, 586..630, 631..675, 676..720, 721..765, 766..810, 811..855, 856..900, 901..945, 946..990, 991..1035, 1036..1080, 1081..1125, 1126..1170, 1171..1215, 1216..1260, 1261..1305, 1306..1350, 1351..1395, 1396..1440, 1441..1485, 1486..1530, 1531..1575, 1576..1620, 1621..1665, 1666..1710, 1711..1755, 1756..1800, 1801..1845, 1846..1890, 1891..1935, 1936..1980, 1981..2025, 2026..2070, 2071..2115, 2116..2160, 2161..2205, 2206..2250, 2251..2295, 2296..2340, 2341..2385, 2386..2430, 2431..2475, 2476..2520, 2521..2565, 2566..2610, 2611..2655, 2656..2700, 2701..2745, 2746..2790, 2791..2835, 2836..2880, 2881..2925, 2926..2970, 2971..3015, 3016..3060, 3061..3105, 3106..3150, 3151..3195, 3196..3240, 3241..3285, 3286..3330, 3331..3375, 3376..3420, 3421..3465, 3466..3510, 3511..3555, 3556..3600, 3601..3645, 3646..3690, 3691..3735, 3736..3780, 3781..3825, 3826..3870, 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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