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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 187919: b. The loan officer rates applicants for credit. Ratings are normally distributed. The mean is 240 and the standard deviation is 60. If 49 applicants are randomly chosen, what is the probability that they will have a rating between 230 and 260? Round z scores to two decimal places
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Question 187880This question is from textbook Elementary Statistics
: A Burglar alarm system has 6 fail safe components. The probability of each failing is 0.05. Find these probabilities using your calculator and the binomial (n,p,x) feature.
a) Exactly 3 will fail
b) Fewer than 2 will fail
c) None will fail
Please help me solve this problem. I don't really know how to determine which one is n,p,or x. For a) i tried n=6 p=0.05 and x=3 after plugging numbers in calculator it gave me =.00214 is this correct? how do i do b or c?This question is from textbook Elementary Statistics
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Question 187926: 1. To reduce operating costs, First UP Bank wants to make sure that the loan department in its branches manage the number of courier packages sent out to appraisers etc. to 15 or less every week. The Bank examined the loan departments of 25 randomly chosen branches and the results show that an average of 14.2 packages with a standard deviation of 2.2 packages were sent during one week in late February. These numbers were fed into the Megastat Add-in in Excel and yield the following output:
Hypothesis Test: Mean vs. Hypothesized Value
15.000 hypothesized value
14.200 mean Packages
2.200 std. dev.
0.440 std. error
25 n
24 df
-1.82 t
.0408 p-value (one-tailed, lower)
At the 0.1 level of significance, is the true average number of packages less than 15? Please state the null and alternative hypothesis as well as the decision rule that you use to arrive at the conclusion.
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Question 187965This question is from textbook Elementary Statistics
: 4.) The average salary for graduates entering the actuarial field is $40.000. If the salaries are normally distributed with a standard deviation of $5000, find the probability that
a.) An individual graduate will have a salary over $45,000.
b.) A group of nine graduates will have a group average over $45,000.
Thank you so much for your help. This question is from textbook Elementary Statistics
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Question 187963This question is from textbook Elementary Statistics
: Using your calculator find the following probabilities, use the standard normal distribution.
a) P(-2.46
b) P(z>-1.77)
I had entered this problem wrong before. How do I enter this on the calculator, do I use normalcdf( ??? for example normalcdf(-2.46,1.14) = .8659 and normacdf(0>-1.77) =.4616 Is this correct? I would really appreciate your help. Thank you. This question is from textbook Elementary Statistics
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Question 187817: During the last hour, a telemarketer dialed 20 numbers and reached 4 busy signals, 3 answering machines, and 13 people. Use this information to determinne the empirical probability the next call will be answered in person.
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Question 187983: The textbook is Applied Statistics by Doane and Seward 2007
ISBN # 978-0-07-296693-0
Chapter 15
15.22 A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question: At α = .05, does vehicle type vary by mall location? (Data are from a project by MBA students Steve Bennett, Alicia Morais, Steve Olson, and Greg Corda.) Vehicle
Vehicle Type Somerset Oakland Great Lakes Jamestown Row /Total
Car 44 49 36 64 193
Minivan 21 15 18 13 67
Full-sized Van 2 3 3 2 10
SUV 19 27 26 12 84
Truck 14 6 17 9 46
Col Total 100 100 100 100 400
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Question 188097: The table shows the results of a survey of 1000 new or used car buyers of a certain model car.
Satisfied Not Satisfied Total
New 300 100 400
Used 450 150 600
Total 750 250 1000
S= event “satisfied” N= event brought a new car”
a. P (N│S) b. P (N∩S) c. P(N│S’) d. P (N’│S) e. P(S)
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Question 188128: This problem mirrors the one I’ll have on the test. What should I use to get the following answers for How many trucks had only late variety peaches? How many had only extra lates? How many had only one type of peach? How many trucks in all went out during the week? You are in charge of distribution for a national fruit and vegetable company. On any given day in the middle of the harvesting season, what is the probability that you will encounter a delivery truck whit contains only one type of peach?
Should I use a venn diagram? Tree? Any suggestions to get me going would be greatly appreciated. If i can work this problem I'll be fine on the test so I'm told.
"Toward the middle of the harvesting season, peaches for canning come in three types: earlies, lates and extra lates. Depending of the expected date of ripening. During a certain week, the following data was recorded at a fruit delivery station: 34 trucks went out carrying early peaches; 61 had late peaches; 50 had extra lates; 25 had earlies and lates; 30 had lates and extra lates; 8 had earlies and extra lates; 6 had all three; 9 had only figs (no peaches at all)."
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Question 188172This question is from textbook
: Here is my question. I am totally lost in this class I am taking. Your help is greatly appreciated. Thank you!
60. In establishing warranties on HDTV sets, the manufacturer wants to set the limits so that few will need repair at manufacturer expense. On the other hand, the warranty period must be long enough to make the purchase attractive to the buyer. For a new HDTV the mean number of months until repairs are needed is 36.84 with a standard deviation of 3.34 months. Where should the warranty limits be set so that only 10 percent of the HDTVs need repairs at the manufacturer’s expense?This question is from textbook
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Question 188242: Could you do this problem?
1.) A debate team surveyed its members' ages, resulting in the data set : 15, 16, 15, 17, 15, 16, 14, 16, 14, 17, 15, 15, 16, 16, 17. What is the experimental probability that a member chosen at random is younger than 16?
Thank you for your help.
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Question 188237: I have tried every thing I know how. Can someone help me?
In Utica, Michigan, 205 of 226 school buses passed the annual safety inspection. In Detroit, Michigan, only 151 of 296 buses passed the inspection. (a) State the hypotheses for a right-tailed test. (b) Obtain a test statistic and p-value. (c) Is normality assured? (d) If significant, is the difference also large enough to be important? (Data are from Detroit Free Press, August 19, 2000, p. 8A.)
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Question 188239: This one has stumped me, can anyone help?
High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this hazard for many hours. A Boeing 727 co-pilot collected 61 noise observations using a handheld sound meter. Noise level is defined as “Low” (under 88 decibels), “Medium” (88 to 91 decibels), or “High” (92 decibels or more). There are three flight phases (Climb, Cruise, Descent). Research question: At α = .05, is the cockpit noise level independent of flight phase? (Data are from Capt. Robert E. Hartl, retired.) Noise
Noise Level Climb Cruise Descent Row Total
Low
6
2
6
14
Medium
18
3
8
29
High
1
3
14
18
Col Total
25
8
28
61
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Question 188238: I just cant get this one.
The results shown below are mean productivity measurements (average number of assemblies completed per hour) for a random sample of workers at each of three plants. Research question: Are the mean hourly productivity levels the same for workers in these three plants? Productivity
Hourly Productivity of Assemblers in Plants
Plant Finished Units Produced Per Hour
A (9 workers)
3.6
5.1
2.8
4.6
4.7
4.1
3.4
2.9
4.5
Â
B (6 workers)
2.7
3.1
5.0
1.9
2.2
3.2
   Â
C (10 workers)
6.8
2.5
5.4
6.7
4.6
3.9
5.4
4.9
7.1
8.4
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Question 188225: CAN SOMEONE PLEASE HELP ME IN STATISTICS? THANK YOU SO MUCH!!!
Jane Doe is Vice President for Human Resources for a large manufacturing company. In recent years she has noticed an increase in absenteeism that she thinks is related to the general health of the employees. Four years ago, in an attempt to improve the situation, she began a fitness program in which employees exercise during their lunch hour. To evaluate the program, she selected a random sample of eight participants and found the number of days each was absent in the six months before the exercise program began and in the last six months. Below are the results. Analyze the results using the proper two-sample test. At the .01 significance level, can he conclude that the number of absences has declined significantly? Explain.
Employee
1
2
3
4
5
6
7
8
Before
6
7
6
7
6
5
4
5
After
4
2
4
4
3
7
2
4
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Question 188173: A jar contains red marbles and green marbles. Ray randomly chooses one marle and places it in his pocket, then randomly chooses a second marble. Find the probability that the first marble is red and the second is green
Marbles
5/8 3/8
Red Green
4/7 3/7 5/7 2/7
Red Green red green\
it is a chart....
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Question 188223: CAN SOMEONE PLEASE HELP ME IN STATISTICS? THANK YOU SO MUCH!!
Does cymbolta reduce the risk of a heart attack? In a kentucky study, researchers gave cymbolta to 2,450 people and an inactive substitute to 2,370 people (average age 58). After 5 years, 58 of the cymbolta group had suffered a heart attack, compared with 97 for the inactive pill. (a) State the appropriate null and alternative hypotheses. (b) Interpret the results at a = .01 (c) Is normality assured? (d) Is the difference large enough to be important?
Hypothesis test for two independent proportions
p1
0.0237
58/2450
58.
2450
p2
0.0409
97/2370
97
2370
pc
0.0322 p (as a decimal)
155/4820 p (as a fraction)
155. X
4820 n
-0.0173 difference
0. hypothesized difference
0.0051 std. error
-3.39 z
.0003 p-value (one-tailed, lower)
-0.0272 confidence interval 95.% lower
-0.0073 confidence interval 95.% upper
0.01 half-width
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Question 188119: Textbook- Applied Statistics
ISBN-13: 978-0-07-296693-0
13.30A researcher used stepwise regression to create regression models to predict BirthRate (births per 1,000) using five predictors: LifeExp (life expectancy in years), InfMort (infant mortality rate), Density (population density per square kilometer), GDPCap (Gross Domestic Product per capita), and Literate (literacy percent). Interpret these results.
Regression Analysis—Stepwise Selection (best model of each size)
153 observations
BirthRate is the dependent variable
p-values for the coefficients
Nvar LifeExp InfMort Density GDPCap Literate s Adj R2 R2
1 .0000 6.318 .722 .724
2 .0000 .0000 .334 .802 .805
3 .0000 .0242 .0000 .261 .807 .811
4 .5764 .0000 .0311 .0000 .273 .806 .812
5 .5937 .0000 .6289 .0440 .0000 .287 .805 .812
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Question 188256This question is from textbook Applied Statistics in Business and Economics
: A sample of 20 pages was taken without replacement 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 of multicolored illustrations, maps, and text). The data (in square millimeters) are shown below:
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 interval for the true mean.
(b) Why might normality be an issue here?
(c) What sample size would be needed to obtain an error of ±10 square millimeters with 99 percent confidence?
(d) If this is not a reasonable requirement, suggest one that is.
This question is from textbook Applied Statistics in Business and Economics
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Question 188289: Salaries for business graduates in D.C. averaged $45,000 with a standard deviation of $49,000 and has a normal distribution. What is the probability that a business graduate will get a higher salary in D.C. than Virginia? The starting salary for a business graduate in Virginia has a normal distribution with a mean of $39,000 and a standard deviation of $2,500.
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Question 188193: 1. If σ is unknown when completing a hypothesis test about the population mean, then the best estimate for the unknown standard deviation is s. _____ T/F
2. The chi-square distribution is used for inferences about the population mean when the standard deviation σ is unknown. ____ T/F
3. The t-distribution is used for all inferences about a population’s variance. ___ T/F
4. When the means of two unrelated samples are used to compare two populations, we are dealing with two dependent means ___ T/F
5. Pretest versus post-test (before versus after) studies are usually independent samples. ____ T/F
6. The number of degrees of freedom for the critical value of t is equal to the smaller of n1 -1 or n2 -1 when making inferences about the difference between two independent means for the case when the degrees of freedom are estimated. ___ T/F
7. The F distribution is a symmetric distribution. ____ T/F
8. Which of the following would be the correct null hypotheses for testing the claim that the proportion of make students (M) who smoke at a particular college is greater than the proportion of female students (F) who smoke?
A. H0: pm ≥ pF
B. H0: pm ≤ pF
C. H0: pm > pF
D. H0: pm < pF
9. Which of the following would be the correct hypotheses for testing the claim that the mean waiting time to be served at a large post office is at least 6.5 minutes?
A. H0: µ ≥ 6.5 and Ha: µ < 6.5
B. H0: µ = 6.5 and Ha: µ≠ 6.5
C. H0: µ ≤ 6.5 vs. Ha: µ > 6.5
D. H0: µ > 6.5 vs. Ha: µ ≥ 6.5
10. The mean age of 25 randomly selected college seniors was found to be 23.5 years, and the standard deviation of all college seniors was 1.3 years. Which of the following is the correct symbol for 1.3 years?
A. µ B. s C. σ D.
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Question 188113: A researcher predicts that listening to music while solving math problems will make a particular brain area more active. To test this, a research participant has her brain scanned while listening to music and solving math problems, and the brain area of interest has a percent signal change of 58. From many previous studies with this same math-problems procedure (but not listening to music), it is known that the signal change in this brain area is normally distributed with a mean of 35 and a standard deviation of 10. Using the .01 level, what should the researcher conclude? Solve this problem explicitly using all five steps of hypothesis testing, and illustrate your answer with a sketch showing the comparison distribution, the cutoff (or cutoffs), and the score of the sample on this distribution. Then explain your answer to someone who has never had a course in statistics (but who is familiar with mean, standard deviation, and Z scores).
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Question 188328: A board game is played with wooden pieces, where each piece shows a number on one side. There are 42 pieces altogether, and each piece shows a number from 1 to 42-each number from 1 to 42 is on exactly one piece- . To begin the game you randomly select 5 pieces.
What is the probability that all the pieces you select are white- answer must be accurate to 4 decimal places.
thanks
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Question 188328: A board game is played with wooden pieces, where each piece shows a number on one side. There are 42 pieces altogether, and each piece shows a number from 1 to 42-each number from 1 to 42 is on exactly one piece- . To begin the game you randomly select 5 pieces.
What is the probability that all the pieces you select are white- answer must be accurate to 4 decimal places.
thanks
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Question 188327: Suppose you have a 10 by 10 checkerboard with alternating brown and white squares. If 5 pieces are randomly placed on the checkerboard.
What is the probability that they will all be in the column #1?
What is the probability that they will all be in the same column?
What is the probability that they will all be placed on white squares?
What is the probability that they will all be placed on squares of the same color?
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Question 188171: 1.A circle with a radius of 1 in. is inscribed in a right triangle with legs of 3 in. and 4 in. If a point is randomly chosen within the triangle, what is the probability that thee point is NOT also in the circle?
2.A movie company surveyed 1000 people. 229 people said they went to see the new movie on Friday, 256 said they went on Saturday. If 24 people saw the movie both nights, what is the probability that a person chosen at random saw the movie on Friday or Saturday?
Thank you for your help.
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Question 188341: A board game is played with wooden pieces, where each piece shows a number on one side. There are 42 pieces altogether, and each piece shows a number from 1 to 42. Each number from 1 to 42 is on exactly one piece.) To begin the game you randomly select 5 pieces.
How many possibilities are there for the numbers you begin with ie in how many different ways can you choose your 5 pieces-the answer is C(42,5) = 850668
The odd numbered pieces are painted blue and the even numbered pieces are painted white. In how many ways could you select your pieces so that they are all white-the answer is C(21,5) = 20349
this is the one I can not get
What is the probability that all the pieces you select are white (your answer must be accurate to 4 decimal places)?
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Question 188356: Hi there I've been having problems with this question all day and I need some help please. I will greatly appreciate it.
In a sample bag of M&M's candy there are 5 brown, 6 yellow, 4 blue, 3 green, and 2 orange.
1. What is the probability of getting 1 green M&M if only 1 is taken at a time?
2. What is the probability of getting 3 yellow M&M's if 3 are taken at a time?
3. What is the probability of getting 1 brown and 2 orange M&M's if 3 are taken at a time?
I'm turning in my homework tomorrow but if someone could give me a second opinion I can see where I went wrong with this problem
Thank you so much for taling the time and helping me I really appreciate it
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Question 188429: if any one could help, I greatly appreciate,
1. In a one-way ANOVA, if the test is conducted and the null hypothesis is rejected, what does this indicate?
A. All the population means are equal
B. At least one of the population means are different
C. The normal distribution should be used instead of the F-distribution to determine the critical values of the test
D. None of the above is correct
2. In a one-way ANOVA, there are three treatments with n1 = 5, n2 = 6 and n3 = 5. The rejection region for this test at the 5% level of significance is
A. F > 3.74
B. F > 4.86
C. F > 4.97
D. F > 3.81
3. The following data show samples of three chain stores in three different locations in one town and the amount of dollars spent per customer per visit. At the 0.05 level, is there a difference in among the means?
Store A Store B Store C
30 42 30
14 28 14
22 20 20
18 35 16
26 49 15
25 28
36
24
4. Choose a variable and collect data for at least three different groups (samples). Compare the means of the three groups using the one-way ANOVA technique. Complete the following:
1. Write a brief statement of purpose of the study
2. Define the population
3. State how the sample was selected
4. What a value did you use?
5. State the hypotheses
6. What was F test value?
7. State the decision
8. Summarize the results.
You may obtain raw data
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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
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