Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 633818: By measuring the amount of time it takes a component of a product to move from one workstation to the next, an engineer has estimated that the standard deviation is 3.33 seconds.
Answer each of the following (show all work):
(A) How many measurements should be made in order to be 90% certain that the maximum error of estimation will not exceed 1.0 seconds?
(B) What sample size is required for a maximum error of 0.5 seconds?
Click here to see answer by ewatrrr(10682)   |
Question 633821: 1. 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 m, the mean for all such families (show all work).
2. Assume that a sample is drawn and z(α/2) = 1.65 and σ = 15. Answer the following questions:
(A)If the Maximum Error of Estimate is 0.05 for this sample, what would be the sample size?
(B)Given that the sample Size is 400 with this same z(α/2) and σ, what would be the Maximum Error of Estimate?
(C) What happens to the Maximum Error of Estimate as the sample size gets larger?
(D) What effect does the answer to C above have to the size of the confidence interval?
Click here to see answer by stanbon(57387) |
Question 633853: for a group of four men , the probability distribution for the number x who live through the next year is as given in the accompanying table. find out the mean and the standard deviation
x | p(x)
0 | 0.05
1 | 0.15
2 | 0.45
3 | 0.25
4 | 0.10
Click here to see answer by stanbon(57387) |
Question 633898: The names of 8 males and 24 females are placed into a jar for a prize drawing. Two names are drawn from the jar without replacement. What is the probability of a male name being drawn on the first draw and a female name being drawn on the second draw?
Click here to see answer by reviewermath(534)  |
Question 633911: A researcher claims that the average age of people who buy lottery tickets is 64. A sample of 30 is selected and their ages are recorded as shown below. The standard deviation is 9. At a
= 0.05 is there enough evidence to reject the researcher’s claim? Show all work.
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 reviewermath(534) |
Question 633937: If the correlation coefficient is -0.275, what is the sign of the slope of the regression line?
- As the correlation coefficient increases from -0.85 to -0.80, do the points of the scatter plot move toward the regression line, or away from it?
Click here to see answer by stanbon(57387) |
Question 634142: Find the correlation coefficient for the data.
- Find the equation for the regression line for the data, and predict the final grade of a student who misses 3.5 days.
Number of absences Final Grade
0 95
1 91
2 82
3 69
4 67
5 58
Click here to see answer by ewatrrr(10682) |
Question 634154: In the poker game Texas hold em each player is dealt two cards. A flush draw is when both cards are of the same suit.
What is the probability of being dealt two spades? (a spades flush draw)
What is the probability of being dealt a flush draw (in any of the 4 suits)?
Click here to see answer by stanbon(57387) |
Question 634161: ***Could someone explain to me how to solve these problems! This is an online class and I am not getting much help from the Professor!" Thanks***
(1) A fair quarter is flipped three times. For each of the following probabilities, use the formula for the binomial distribution and a calculator to compute the requested probability. Next, look up the probability in the binomial probability distribution table. (Enter your answers to three decimal places.)
(a) Find the probability of getting exactly three heads. = ________
(b) Find the probability of getting exactly two heads. = ________
(c) Find the probability of getting two or more heads. = ________
(d) Find the probability of getting exactly three tails. = _______
(2) The one-time fling! Have you ever purchased an article of clothing (dress, sports jacket, etc.), worn the item once to a party, and then returned the purchase? This is called a one-time fling. About 20% of all adults deliberately do a one-time fling and feel no guilt about it! In a group of six adult friends, what is the probability of the following? (Round your answers to three decimal places.)
(a) no one has done a one-time fling = ________
(b) at least one person has done a one-time fling = ________
(c) no more than two people have done a one-time fling = ________
(3) What percentage of the area under the normal curve lies between μ − σ and μ + σ?
What percentage of the area under the normal curve lies between μ − 3σ and μ + 3σ?
(4) Sketch the area under the standard normal curve over the indicated interval and find the specified area. (Round your answer to four decimal places.)
The area between z = −2.18and z = 1.37 is ________
(5) Let z be a random variable with a standard normal distribution. Find the indicated probability. (Round your answer to four decimal places.)
P(−1.25 ≤ z ≤ 2.40) = ________
(6) Assume that x has a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)
μ = 4.4; σ = 2.3
P(3 ≤ x ≤ 6) = ________
(7) Assume that x has a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)
μ = 29; σ = 3.9
P(x ≥ 30) = ________
(8) Find z such that 68% of the standard normal curve lies to the right of z. (Round your answer to two decimal places.)
z = ________
(9) Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 50 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 ml/kg (milliliters plasma per kilogram body weight). Assume that σ = 7.80 ml/kg for the distribution of blood plasma.
(a) Find a 99% confidence interval for the population mean blood plasma volume in male firefighters. What is the margin of error? (Round your answers to two decimal places.)
lower limit = ________
upper limit = ________
margin of error = ________
(10) For this problem, carry at least four digits after the decimal in your calculations. Answers may vary slightly due to rounding.
A random sample of 5427 physicians in Colorado showed that 3062 provided at least some charity care (i.e., treated poor people at no cost).
(a) Let p represent the proportion of all Colorado physicians who provide some charity care. Find a point estimate for p. (Round your answer to four decimal places.) = 0.5642
(b) Find a 99% confidence interval for p. (Round your answers to three decimal places.)
lower limit = ________
upper limit = ________
Click here to see answer by ewatrrr(10682) |
Question 634174: The amount of liquid a paper towel can absorb will be use to marked the paper towel. Suppose a sample of 15 new towels average 12.5 grams with standard deviation of 1.15 grams. the previous version of this paper towel absorbed an average of 12 grams. With the =5%, we can conclude that, on average
the new towel absorbs more than the previous one since the critical test value is 1.645
the new towel absorbs more than the previous one since the critical test value is 1.761
the new towel does not absorb more than the previous one since the critical test value is 1.761
the new towel does not absorb more than the previous one since the critical test value is 1.645
Click here to see answer by stanbon(57387) |
Question 634173: The amount of liquid a paper towel can absorb will be use to marked the paper towel. Suppose a sample of 15 new towels average 12.5 grams with standard deviation of 1.15 grams. the previous version of this paper towel absorbed an average of 12 grams. Calculate the test statistics for this problem
t=1.6839
z=1.6839
z=0.4348
t=0.4348
Click here to see answer by stanbon(57387) |
Question 634186: A bag contains five purple ("P") blocks and one yellow ("Y") blocks. Without looking into the bag you reach in, take out a block, return the block to the bag, and then repeat the same process a number of times. Which of the following sequences of selected blocks is more likely?
YPPYPP
YYYPPP
YYYPP
Click here to see answer by stanbon(57387) |
Question 634191: The college Physical Education Department offered an Advanced First Aid course last summer. The scores on the comprehensive final exam were normally distributed, and the z scores for some of the students are shown below.
Robert, 1.16 Juan, 1.87 Susan, –2.2
Joel, 0.00 Jan, –0.89 Linda, 1.78
If the mean score was μ = 151 with standard deviation σ = 15, what was the final exam score for each student? (Round your answers to the nearest whole number.)
Joel = ________
Jan = ________
Juan = ________
Susan = ________
Click here to see answer by ewatrrr(10682) |
Question 634196: At General Hospital, nurses are given performance evaluations to determine eligibility for merit pay raises. The supervisor rates the nurses on a scale of 1 to 10 (10 being the highest rating) for several activities: promptness, record keeping, appearance, and bedside manner with patients. Then an average is determined by giving a weight of 3 for promptness, 1 for record keeping, 2 for appearance, and 4 for bedside manner with patients. What is the average rating for a nurse with ratings of 8 for promptness, 7 for record keeping, 7 for appearance, and 10 for bedside manner? (Round your answer to one decimal place.)
Click here to see answer by richwmiller(9143)  |
Question 634196: At General Hospital, nurses are given performance evaluations to determine eligibility for merit pay raises. The supervisor rates the nurses on a scale of 1 to 10 (10 being the highest rating) for several activities: promptness, record keeping, appearance, and bedside manner with patients. Then an average is determined by giving a weight of 3 for promptness, 1 for record keeping, 2 for appearance, and 4 for bedside manner with patients. What is the average rating for a nurse with ratings of 8 for promptness, 7 for record keeping, 7 for appearance, and 10 for bedside manner? (Round your answer to one decimal place.)
Click here to see answer by ewatrrr(10682) |
Question 634193: The following table shows the Myers-Briggs personality preferences for a random sample of 406 people in the listed professions. E refers to extroverted and I refers to introverted.
Personality Type
Occupation EI Row Total
Clergy (all denominations) 67 40 107
M.D. 67 95 162
Lawyer 56 81 137
Column Total 190 216 406
Use the chi-square test to determine if the listed occupations and personality preferences are independent at the 0.05 level of significance.
(a) What is the level of significance? = ________
(b) Find the value of the chi-square statistic for the sample. (Round the expected frequencies to at least three decimal places. Round the test statistic to three decimal places.) = ________
What are the degrees of freedom?
(c) Find or estimate the P-value of the sample test statistic. (Round your answer to three decimal places.)
Click here to see answer by stanbon(57387) |
Question 634256: The Cadet is a popular model of sport utility vehicle, known for its relatively high resale value. The bivariate data given below were taken from a sample of fifteen Cadets, each bought "new" two years ago and each sold "used" within the past month. For each Cadet in the sample, we have listed both the mileage, X (in thousands of miles), that the Cadet had on its odometer at the time it was sold used, and the price, y (in thousands of dollars), at which the Cadet was sold used. These data are shown graphically in the scatter plot in Figure 1. Also given are the products of the mileages and used selling prices for each of the fifteen Cadets. (These products, written in the column labelled "xy" may aid in calculations.)
Mileage X Used selling price y xy
23.8 27.7 659.26
23.1 30.7 709.17
26.6 31.2 829.92
27.9 30.0 837
23.1 33.0 762.3
23.7 30.1 713.37
20.9 31.7 662.53
23.8 27.8 661.64
21.4 30.4 650.56
37.4 22.2 830.28
25.9 26.5 686.35
34.2 25.5 872.10
29.3 27.2 796.96
27.8 26.1 725.58
15.4 34.6 532.84
What is the value of the sample correlation coefficient for these data? Round answer to at least three decimal places.
Click here to see answer by lynnlo(4164) |
Question 634282: Intersection and conditional probability
Suppose that a certain college class contains students. Of these, are juniors, are history majors, and are neither. A student is selected at random from the class.
(a) What is the probability that the student is both a junior and a history major?
(b) Given that the student selected is a junior, what is the probability that she is also a history major?
Write your responses as fractions.
(If necessary, consult a list of formulas.)
Click here to see answer by lynnlo(4164) |
Question 634289: Suppose a business owner has a choice of five locations in which to establish her business . She decides to rank each location according to certain criteria, such as price of the store and parking facilities. How many different ways can she rank five cities?
Click here to see answer by lynnlo(4164) |
Question 634339: Two voters were asked if they are in favor or against the "Charter Change" (cha-cha) of the present administration. The responses are Y=yes, N=no, and S=sometimes.
a. Write the sample space on the possible outcome of their response.
b. Find the probability that exactly 1 said yes.
c. Find the probability that at least 1 said sometimes.
d. Find the probability that at most 2 said no.
Click here to see answer by ewatrrr(10682) |
Question 634279: In some reports, the mean and coefficient of variation are given. For instance, one report gives the average number of physician visits by males per year. The average reported is 3.2, and the reported coefficient of variation is 1.4%. Use this information to determine the standard deviation of the annual number of visits to physicians made by males. (Round your answer to three decimal places.)
Click here to see answer by ewatrrr(10682) |
Question 634250: 1. A meal at a certain restaurant consists of 3 entrees chosen from a group of 15 possible entrees, find the number of possible meal combinations.
So I tried multiply 3 by 15 and that didn't work and I tried multiplying 1/15 x 1/15 x 1/15. I know the possible answers are:
2,730
6
455
or 217,945,728,000
Your help is greatly appreciated! Thank you.
Click here to see answer by ewatrrr(10682) |
Question 634248: The number of cell phone minutes used by high school seniors follows a normal distribution with a mean of 500 and a standard deviation of 50.
1.What is the probability that a student uses fewer than 600 minutes?
2.What is the probability that a student uses fewer than 400 minutes?
3.What is the probability that a student uses more than 350 minutes?
4.What is the probability that a student uses more than 580 minutes?
Click here to see answer by ewatrrr(10682) |
Question 634253: The monthly number of permits granted for building houses in a large city is seasonal (there tend to be more permits granted for construction during spring and summer months than during winter months). The following table shows the monthly seasonal indexes for building permits:
JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC
0.80 0.84 0.91 1.14 1.36 1.25 1.15 1.08 0.89 0.91 0.88 0.82
Using several years of permit data, beginning in February of 2000 (i.e., t=1 corresponds to February of 2000), an analyst reported that the trend line that describes the monthly permit data is of the form Tt = 717+5t. Assuming that a multiplicative model can be used to describe the building permit data, generate a forecast for the number of building permits that you expect will be granted in June of 2005.
Click here to see answer by stanbon(57387) |
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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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