Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 326339: Alex has won a radio contest that allows him to draw three bills that he can keep from a bag that contains 50 five-dollar bills, 20 ten-dollar bills, 15 twenty-dollar bills, 10 fifty-dollar bills, and 5 hundred-dollar bills. What is the probability that Alex will get $300?
A 1/8000 B 5/100 C 1/16170 D 3/50000 E 3/40000
Click here to see answer by Edwin McCravy(8909)   |
Question 326271: The number of times a person blinks was studied for a sample of 35 people. The sample's average was 47 blinks per minute. The population standard deviation is 7.8 blinks per minute. What is the 99% confidence interval for the population average?
Click here to see answer by stanbon(57387) |
Question 326269: On a test given to all high school students in the state of Maryland, the average score was 82 and the standard deviation was 4.2. If a sample of 100 students is randomly selected, what is the probability that the sample's average is less than 83?
Click here to see answer by stanbon(57387) |
Question 326267:
On a test given to all high school students in the state of Maryland, the average score was 82 and the standard deviation was 4.2. If one student is randomly selected, what is the probability that this student scored above 90?
Click here to see answer by Fombitz(13828)  |
Question 326380: The managers of a brokerage firm are interested in finding out if the number of new clients a broker brings into the firm affects the sales generated by the broker. They sample 12 brokers and determine the number of new clients they have enrolled in the last year and their sales amounts in thousands of dollars. These data are presented in the table that follows.
The least squares estimate of the Y-intercept is ________.
Click here to see answer by stanbon(57387) |
Question 326384: The managers of a brokerage firm are interested in finding out if the number of new clients a broker brings into the firm affects the sales generated by the broker. They sample 12 brokers and determine the number of new clients they have enrolled in the last year and their sales amounts in thousands of dollars. These data are presented in the table that follows.
Broker Clients Sales
1 27 52
2 11 37
3 42 64
4 33 55
5 15 29
6 15 34
7 25 58
8 36 59
9 28 44
10 30 48
11 17 31
12 22 38
Referring to Table 13-4, the least squares estimate of the Y-intercept is ________.
Click here to see answer by Fombitz(13828) |
Question 326435: PROBLEM 1
The 2003 Zagat Restaurant Survey provides food, décor, and service ratings for some of the top restaurants
across the United States. For 15 top-ranked restaurants located in Boston, the average price of a dinner
including, one drink and tip, was $48.60. You are leaving for a business trip to Boston and will eat dinner at
three of these restaurants. Your company will reimburse you for a maximum of $50 per dinner. Business
associates familiar with these restaurants have told you that the meal cost at one-third of these restaurants
will exceed $50. Suppose that you randomly select three restaurants for dinner.
a. What is the probability that none of the meals will exceed the cost covered by your company?
b. What is the probability that one of the meals will exceed the cost covered by your company?
c. What is the probability that two of the meals will exceed the cost covered by your company?
d. What is the probability that all three of the meals will exceed the cost covered by your company?
PROBLEM 2
Military radar and missile detection system are designed to warn a country of an enemy attack. A
reliability question is whether a detection system will be able to identify an attack and issue a warning.
Assume that a particular detection system has a .90 probability of detecting a missile attack.
a. What is the probability that single detection system will detect the attack?
b. If two detection systems are installed in the same area and operating independently, what is the
probability that at least one of the systems will detect the attack?
c. If three systems are installed, what is the probability that at least one of the systems will detect
the attack?
d. Would you recommend the multiple detection systems be used? Explain.
I would recommed 3 detection systems be installed. Like a wise man says there is saftey in numbers
PROBLEM 3
Phone calls arrive at the rate of 48 per hour at the reservation desk for Regional Airways.
a. Compute the probability of receiving three calls in a 5-minute interval of time.
b. Compute the probability of receiving exactly 10 calls in 15 minutes.
c. Suppose, no calls are currently on hold. If the agent takes 5 minutes to complete the current
call, how many callers do you expect to be waiting by that time? What is the probability that
none will be waiting?
d. If no calls are currently being processed, what is the probability that the agent can take 3 minutes
for personal time without being interrupted by a call?
PROBLEM 4
Trading volume on the New York Stock Exchange is heaviest during the first half hour (early morning)
and last half hour (late afternoon) of the trading day. The early morning trading volumes (millions of
shares) for 13 days in January and February are shown here (Barron's, January 23, 2006;
February 13, 2006; and February 27, 2006)
Trading Volume (millions of shares)
163
171
174
180
194
198
201
202
211
211
212
214
265
The probability distribution of trading volume is approximately normal.
a. Compute the mean and standard deviation to use as estimates of the population mean and
standard deviation.
b. What is the probability that, on a randomly selected day, the early morning trading volume will be
less than 180 million shares?
c. What is the probability that, on a randomly selected day, the early morning trading volume will
exceed 230 million shares?
d. How many shares would have to be traded for the early morning trading volume on a particular
day to be among the busiest 5% of days?
PROBLEM 5
The average score for male golfers is 95 and the average score for female golfers is 106 (Golf Digest,
April 2006). Use these values as the population means for men and women and assume that the
population standard deviation σ = 14 strokes for both. A simple random sample of 30 male golfers
and another simple random sample of 45 female golfers will be taken.
a. Show the sampling distribution of x for male and female golfers.
b. What is the probability that the sample mean is within 3 strokes of the populations mean for the
sample of male golfers?
c. What is the probability that the sample mean is within 3 strokes of the populations mean for the
sample of female golfers?
d. In which case, part (b) or part (c), is the probability of obtaining a sample mean within 3 strokes of
the population mean higher? Why?
PROBLEM 6
Playbill magazine reported that the mean annual household income of its readers is $119,155.
(Playbill, January 2006). Assume this estimate of the mean annual household income is based on
a sample of 80 households, and based on past studies, the population standard deviation is known
to be σ = $30,000.
a. Develop a 90% confidence interval estimate of the population mean.
b. Develop a 95% confidence interval estimate of the population mean.
c. Develop a 99% confidence interval estimate of the population mean.
Click here to see answer by Fombitz(13828) |
Question 326468: PROBLEM 6
Playbill magazine reported that the mean annual household income of its readers is $119,155.
(Playbill, January 2006). Assume this estimate of the mean annual household income is based on
a sample of 80 households, and based on past studies, the population standard deviation is known
to be σ = $30,000.
a. Develop a 90% confidence interval estimate of the population mean.
b. Develop a 95% confidence interval estimate of the population mean.
c. Develop a 99% confidence interval estimate of the population mean.
Click here to see answer by Fombitz(13828) |
Question 326531: I have a homework question that I need explained in detail.
There are 6 circles in a row, the first yellow, the second is green, the third, fourth and fifth are orange and the sixth is yellow.
Assume 1 circle is selected at random and each circle is equally likely to be selected. Determine the probability of selecting.
Click here to see answer by user_dude2008(1861) |
Question 326578: I am not sure what to use since they are asking for a probabilty that "none fail". It reads:
An alarm system has ten fail-safe components. The probability of each failing is .07. What is the probability that none will fail?
I have made it this far...
n=10
p=.07(?)
I don't know where to go from here.
Click here to see answer by user_dude2008(1861) |
Question 326570: Airlines have to estimate the weights of passengers. Assume that men have weights that are normally distributed with a mean of 172 pounds and a standard devation of 29 pounds. Find the probability that among 213 male passengers, the mean weight is greater than 175 pounds.
Give your answer to four decimal places.
Click here to see answer by stanbon(57387) |
Question 326568: Engineers want to design seats in commercial airlines so that they are wide enough to fit 98% of all males.
Men have hip breadths that are normally distributed with a mean of 14.4 inches and a standard deviation of 1.0 inches.
What seat width would fit all men except the tallest 2%?
Round your answer to two decimal places.
Click here to see answer by stanbon(57387) |
Question 326558: A number greater than 3, given that the circle is yellow.
There are 6 circles. The 1st is yellow, the 2nd is green, the 3rd, 4th, and 5th are orange and the 6th is yellow.
Assume that 1 circle is selected at random and each circle is equally likely to be selected. Determine the probability of selecting.
Click here to see answer by stanbon(57387) |
Question 326552: A debate club consists of 12 men and 10 women. a) In how many ways can the club select a president, vice president and treasurer? (Assume no person can hold two offices at once) b) In how many ways can the club select a president, vice president and treasurer where all three officers are male? c) What is the probability that all three officers are male? d) What is the probability of selecting at least one female officer?
Click here to see answer by stanbon(57387) |
Question 326600: If you draw a card from a 52 card deck what is the probability of drawing a jack of hearts given
a)The Card drawn is a red card
b)The card drawn is a heart
c)The card drawn is a jack
d)The card drawn is a spade
What I've tried so far.
a)On this problem I'm not sure what kind of prob to use. wether the fraction or nCr. But the way I approached this problem I did prob of a jack of hearts is 1/52 since there is only one of that specific card. And the card is a red card is half of that since it's either black or red. so 1/26 is my guess.
However, for b), I am not sure how to get the answer there.
Click here to see answer by solver91311(16897)  |
Question 326613: Please some one i need some help on these questions i missed my class and i am not understanding how to do them.
1. Construct a scatter plot using excel for the given data. Determine whether there is a positive linear correlation, negative linear correlation, or no linear correlation. Complete the table and find the correlation coefficient r. (References: example 1 - 4 pages 498 - 500; end of section exercises 15 - 22 pages 508 - 509)
The data below are the number of absences and the final grades of 9 randomly selected students from a statistics class.
Absences, x 4 7 10 8 13 6 19 12 9
Final grade, y 99 87 81 83 72 93 56 77 83
a: Scatter plot (3.5 points)
b: Type of correlation (positive linear correlation, negative linear correlation, or no linear correlation) (2.5 points)
c: Complete the table and find the correlation coefficient r.
(6 points)
x y xy x2 y2
4 99
7 87
10 81
8 83
13 72
6 93
19 56
12 77
9 83
Use the last row of the table to show the column totals.
n = 9
2. Construct a scatter plot including the regression line using excel for the given data. Determine whether there is a positive linear correlation, negative linear correlation, or no linear correlation. Complete the table and find the correlation coefficient r. The data below are the gestation periods, in months, of randomly selected animals and their corresponding life spans, in years.
Gestation, x 8 2.1 1.3 1 11.5 5.3 3.8 24.3
Life span, y 30 12 6 3 25 12 10 40
a: Scatter plot with regression line (3.5 points)
b: Type of correlation (positive linear correlation, negative linear correlation, or no linear correlation) (2.5 points)
c: Complete the table and find the correlation coefficient r.
(7 points)
x y xy x2 y2
8 30
2.1 12
1.3 6
1 3
11.5 25
5.3 12
3.8 10
24.3 40
Use the last row of the table to show the column totals.
n = 8
r =
3. Using the r calculated in problem 2c test the significance of the correlation coefficient using = 0.01 and the claim rho 0. Use the 7-steps hypothesis test shown at the end of this project. (References: example 7 page 505; end of section exercises 23 - 28 pages 510 - 511) (7 points) (Round the computed t to 3 decimal places.)
1. H0 :
Ha :
2. =
3.
4. the critical value(s) t0
5. Rejection region:
6. Decision:
7. Interpretation:
Section 9.2: Linear Regression
(References: example 1 - 3 pages 514 - 516; end of section exercises 13 -22 pages 518 - 520)
4. The data below are the gestation periods, in months, of randomly selected animals and their corresponding life spans, in years.
Gestation, x 8 2.1 1.3 1 11.5 5.3 3.8 24.3
Life span, y 30 12 6 3 25 12 10 40
a. Find the equation of the regression line for the given data. Round the line values to the nearest two decimal places. (4 points) Show your work.
b. Using the equation found in part a, predict the life span when the gestation is 10 months. Round to the nearest absence. (4 points)
Click here to see answer by Fombitz(13828) |
Question 326792: A spends 2 hours on patient medications, 5 hours on patient checks and 1 hour helping doctors. If the next day is spent exactly as the previous, what are the chances of completing patient checks or helping doctors?
Click here to see answer by Fombitz(13828) |
Question 326836: The probability that a person will have 0,1, or 2 dental checkups per year is 0.3, 0.6, and 0.1 repectively. If seven people are picked at random, what is the probability that two will have no checkups, four will have one checkup, and one will have two checkups in the next year?
A) 0.012
B) 0.018
C) 0.122
D) 0.588
All I can figure out and I am not sure if this is right is: (7!/2!*4!*1!)
Click here to see answer by galactus(183)  |
Question 326858: I was wondering if you can help me with this question? I am thinking B.
What statistic from the output provides us with an estimate of the amount of variablility in Weight that is being explained by Height?
A) S
B) R-Sq
C) The Coefficient for Height
Thanks,
Kim
Click here to see answer by stanbon(57387) |
Question 326869: What is the probability of drawing one 5 from a pack of cards if you are dealt 4 cards? And
If 3 dice are rolled what is the probability of throwing one 6.
And what is the probability of throwing two 6's.
I would be very very grateful to see your working out for these questions
Click here to see answer by solver91311(16897) |
Question 326911: in a particular game, a fair die is tossed. if the number of spots showing is a six, you win $6, if the number of spots showing is a five, you win $3, and if the number of spots showing is 4, you win $1. if the number of spots showing is 1, 2, or 3 you win nothing. you are going to play the game twice.
The probability that you win over $10 in total on the two plays of the game is:
a- 1/6
b- 1/3
c- 1/36
d- 1/4
thanks
Click here to see answer by solver91311(16897) |
Question 326932: Can I get some help with this Stats question? I have no idea where to start.
A group of adults aged 20 to 80 were tested to see how far away they could first hear an ambulance coming towards them. An equation describing the relationship between distance (in feet) and age was found to be
Distance = 600 - 3 × Age
Based on the equation, what is the strength of the relationship between distance and age?
A) There is a weak relationship.
B) There is a strong relationship.
C) Strength can’t be determined from the equation.
D) There is no relationship.
Thanks,
Dave
Click here to see answer by stanbon(57387) |
Question 327011: Suppose 39 newly created pairs of jeans are placed in a bin to be checked for quality. Of these, 4 will not be of high enough quality to sell. Suppose that two pairs of jeans are randomly selected, without replacement, from the bin. What is the chance that both pairs of jeans selected will be substandard? Show step by step work! Give solution as a reduced fraction in lowest terms and approximated to the nearest ten thousandth
Click here to see answer by stanbon(57387) |
Question 228469: One personality test available on the World Wide Web has a subsection designed to assess the "honesty" of the test-taker. After taking the test and seeing your score for this subsection, you're interested in the mean score, , among the general population on this subsection. The website reports that is , but you believe that is less than . You decide to do a statistical test. You choose a random sample of people and have them take the personality test. You find that their mean score on the subsection is and that the standard deviation of their scores is .
Based on this information, answer the questions below.
Click here to see answer by me74(1) |
Question 327054: The Human Resources Director for a large company is studying absenteeism among hourly workers. A sample of 120 day shift employees showed 15 were absent more than five days last year. A sample of 80 afternoon employees showed 18 to be absent five or more times. At the 0.01 significance level can we conclude that there is a higher proportion of absenteeism among afternoon employees?
a. State the null and alternate hypotheses.
b. State the decision rule.
c. Compute the value of the test statistic.
d. Compute the p-value.
e. What is your decision regarding the null hypothesis?
Click here to see answer by stanbon(57387) |
Question 326968: I am still having trouble on this can some one please make it a little clearer for me on how to get the answer to this. i am having trouble showing the work on this.
1. Construct a scatter plot using excel for the given data. Determine whether there is a positive linear correlation, negative linear correlation, or no linear correlation. Complete the table and find the correlation coefficient r. (References: example 1 - 4 pages 498 - 500; end of section exercises 15 - 22 pages 508 - 509)
The data below are the number of absences and the final grades of 9 randomly selected students from a statistics class.
Absences, x 4 7 10 8 13 6 19 12 9
Final grade, y 99 87 81 83 72 93 56 77 83
a: Scatter plot (3.5 points)
b: Type of correlation (positive linear correlation, negative linear correlation, or no linear correlation) (2.5 points)
c: Complete the table and find the correlation coefficient r.
(6 points)
x y xy x2 y2
4 99
7 87
10 81
8 83
13 72
6 93
19 56
12 77
9 83
Use the last row of the table to show the column totals.
n = 9
Click here to see answer by Fombitz(13828) |
Question 327091: All of the arrangements of the letters in the word ALGEBRA are written on
a list, and one of the arrangements is selected at random. What is the
probability that the selected arrangement contains a double-A?
Click here to see answer by galactus(183) |
Question 327103: I am wondering if I could get confirmation for this problem. I think you would square the -.6 to get -.36. But I am not sure.
If the correlation between a response variable Y and explanatory variable X is - 0.6, what is the value that defines how much variation in Y is explained by X?
A) 6%
B) 36%
C) - 36%
D) - 6%
Thanks,
Maria
Click here to see answer by stanbon(57387) |
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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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