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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 170987: The following data represents the age (in weeks) at which babies first crawl based on survey of 12 mothers:
52, 30, 44, 35, 26, 47, 37, 56, 39, 26, 39, 28
Assume that the data comes from a normal distribution. Conduct a 95% confidence interval for the mean age at which a baby first crawls.
Click here to see answer by stanbon(26259)   |
Question 171130: woul you please show me how to find the probability of randomly choosing a red marble from the given number of red and white marbles?
and also how to find the odds.
1.number of red marbles - 16
total number of marbles - 64
Click here to see answer by solver91311(5072)  |
Question 171110: A teacher will take 10 questions from a study guide of 20 questions for a quiz. If a student knows the answer to 15 of the questions, what is the probability that student will get:
all 10 questions correct?
exactly 8 questions correct?
at least 9 questions correct?
I was able to solve the first question, the answer being (21/1292) by evaluating 15(nCr)10 / 20(nCr)10, but I have no idea how to do the other two questions. Even after I was given the answers, I couldn't figure out how to get to them.
Answer to second one is (225/646)
Answer to third one is (49/323)
Please Help!
Click here to see answer by oscargut(682)  |
Question 171194This question is from textbook
: How many batting lineups are there for the nine players of a baseball team if the center fielder must bat fourth and the pitcher last?
I came up with the answer 7
Am I correct?This question is from textbook
Click here to see answer by stanbon(26259) |
Question 171205This question is from textbook
: the speeds in miles per hour of 30 cars were checked by radar, the data is as follows:
62 67 69 72 75 60 58 86 74 68
56 67 82 88 90 54 67 65 64 68
74 65 58 75 67 65 66 64 45 64
Find the upper and lower quartiles?This question is from textbook
Click here to see answer by Mathtut(3670) |
Question 171181: I'm lost on a portion of this question. Will you please help!!
Find the mean, median, mode and standard deviation of the data. Round to the nearest hundreth, if necessary. (The data is as follows:
456
306
160
363
376
935
54
349
I came up with the mean=374.88
I cam up with the mdeian=354.5
The mode I got 0 because no number was repeated
Now how do I do the standard deviation? Will please show me the steps to find the standard deviation?
Thanks so much
Click here to see answer by Mathtut(3670) |
Question 171471This question is from textbook
: I just want someone to double check my answer.
A club consists of 10 members. In how many different ways can a group of 3 people be selected to go on a European trip?
I came up with 9 different ways.
Is this answer correct?This question is from textbook
Click here to see answer by Alan3354(6059)  |
Question 171483This question is from textbook
: The points M, N, O, P, and Q in the following figure represents exits on a highway (the numbers represent miles). An accident occurs at random between points M and Q. What is the probability that it has occurred between N and O?
M____5_________N_________8______O_______4_________P_______3________Q
This question is from textbook
Click here to see answer by solver91311(5072) |
Question 171473This question is from textbook
: I need some help with this problem.
Following are the lengths in yards of the nine holes of the University Golf Course. Find each of the following measures with respect to the lengths of the holes:
160 360 330
350 180 460
480 450 380
I have to find the standard deviation?This question is from textbook
Click here to see answer by Mathtut(3670) |
Question 171510This question is from textbook
: I need someone to double check my answer.
One card is slected at random from a ordinary set of 52 cards. Find the probability of each of the following events: a spade and a 5 are drawn
4 fives = heart, diamond, clover and spade
14 spades - 1(5 of spades) = 13 spades
4/52 = 1/13
13/13 = 1
I came up with answer of 1%This question is from textbook
Click here to see answer by Mathtut(3670) |
Question 171510This question is from textbook
: I need someone to double check my answer.
One card is slected at random from a ordinary set of 52 cards. Find the probability of each of the following events: a spade and a 5 are drawn
4 fives = heart, diamond, clover and spade
14 spades - 1(5 of spades) = 13 spades
4/52 = 1/13
13/13 = 1
I came up with answer of 1%This question is from textbook
Click here to see answer by solver91311(5072) |
Question 171554This question is from textbook
: I need someone to double check my answer please:
The heights of 1000 girls at East High School were measured, and the mena was found to be 64 inches., with a standard deviation of 2 inches. If the heights are approximately normally distributed, about how many of the girls are between 60 and 64 inches?
I came up with the answer of 0.99997This question is from textbook
Click here to see answer by jim_thompson5910(13787) |
Question 171574: I NEED URGENT HELP WITH THESE TWO QUESTIONS. MY STEPS WERE CORRECT BUT CALCULATIONS ARE WRONG. I WANT TO REVIEW FOR MY FINALS. ALL TUTOR YOU ARE WELCOME TO ANSWER. PAID OR NOT. THANKS A BUNCH! I NEED EXPLAINED SOLUTIONS.
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
Identify the null hypothesis, alternative hypothesis, test statistic, P-value, conclusion about the null hypothesis, and final conclusion that addresses the original claim.
6) The health of employees is monitored by periodically weighing them in. A sample of 54 employees has a mean weight of 183.9 lb. Assuming that ! is known to be 121.2 lb, use a 0.10 significance level to test the claim that the population mean of all such employees
weights is less than 200 lb.
Test the given claim using the traditional method of hypothesis testing. Assume that the sample has been randomly selected from a population with a normal distribution.
7) A large software company gives job applicants a test of programming ability and the mean for that test has been 160 in the past. Twenty-five job applicants are randomly selected from one large university and they produce a mean score and standard deviation of 183 and 12, respectively. Use a 0.05 level of significance to test the claim that this sample comes from a population with a mean score greater than 160.
Click here to see answer by stanbon(26259) |
Question 171643This question is from textbook
: Please double check my work
Bill needs an average of 80 on four tests in science to make the honor roll. What is the lowest score he can receive on hte fourth test if his first three scores are 73, 96, and 89?
I added 73+96+89 = 258
then I divided 258/3 and came up with the answer of 86
86 is the lowest grade he can make
did I do this right?This question is from textbook
Click here to see answer by nerdybill(2446)  |
Question 171643This question is from textbook
: Please double check my work
Bill needs an average of 80 on four tests in science to make the honor roll. What is the lowest score he can receive on hte fourth test if his first three scores are 73, 96, and 89?
I added 73+96+89 = 258
then I divided 258/3 and came up with the answer of 86
86 is the lowest grade he can make
did I do this right?This question is from textbook
Click here to see answer by Earlsdon(4898) |
Question 171641This question is from textbook
: Please double check my work
The Ph of a patients blood was measured periodically during one week, and the measured values were 7.37, 7.40, 7.45, 7.45, and 7.44. Find the standard deviation and variance for the data. Round the results to the nearest thousandth.
I added 7.37 + 7.40 + 7.45 + 7.45 + 7.44 = 37.11
then I divided 37.11/ 5 and came up with the answer of 7.4222
Did I do this right?This question is from textbook
Click here to see answer by stanbon(26259) |
Question 171639This question is from textbook
: Please double check my work
Two marbles are drawn without replacement from a box with 3 white, 2 green, 2 red, and 1 blue marble. Find the probability. The first marble is white and the second marble is blue.
p(white) = 3/8
p(green) = 2/8 = 1/4
p(red) = 2/8 = 1/4
p(blue) = 1/8
I came up with the answer of 6/8. Am I right?This question is from textbook
Click here to see answer by Earlsdon(4898) |
Question 171736: Could someone please help, I do not fully understand this question thanks in advance
Suppose you read the average family in virgina has 2.41 children. What average is being used to describe the data? Explain
Click here to see answer by Alan3354(6059) |
Question 171717This question is from textbook
: I need someone to double check my work for me please
The pH of a patient's blood was measured periodically diring one week, and the measured values were 7.37, 7.40, 7.45, 7.45, and 7.44. Find the standard deviation and variance for the data. Round the results to the nearest thousandths.
The mean is 7.4222
7.37 - 7.4222 = 0.0522 then squared = 0.00272484
7.40 - 7.4222 = 0.0222 then squared = 0.00049284
7.45 - 7.4222 = 0.0278 then squared = 0.00077284
7.45 - 7.4222 = 0.0278 then squared = 0.00077284
7.44 - 7.4222 = 0.0178 then squared = 0.00031684
then I added all the squared answers together and got 0.0050802
then I divided 0.0050802 by 5 and the result was 0.00101604
The S.D is 0.00101604 Am I right on this?
I dont know how to do the variance, can someone help me on that part?This question is from textbook
Click here to see answer by stanbon(26259) |
Question 171714This question is from textbook
: I need someone to double check my work.
Two dice are rolled. Find the probability that the score on the dice is either 7 or 9?
Possibilities for 7 are (4,3)(5,2)(6,1) which = 3/36 = 1/12 = 0.083333 (8%)
Possibilities for 9 are (6,3)(4,5)which = 2/36 = 1/18 = 0.055555 = (6%)
Did I work these problems right?
This question is from textbook
Click here to see answer by stanbon(26259) |
Question 172026: a school board plans to merge 2 schools into a school of 1000 students of which 42% will be african american. One of the schools has a 10% african american student body and the3 other has a 90% african american student body. What is the studen population in each of the two schools?
Click here to see answer by Earlsdon(4898) |
Question 172026: a school board plans to merge 2 schools into a school of 1000 students of which 42% will be african american. One of the schools has a 10% african american student body and the3 other has a 90% african american student body. What is the studen population in each of the two schools?
Click here to see answer by josmiceli(3003) |
Question 172110: A survey of undergraduate students in the School of Business at Northern University revealed the following regarding the gender and majors of the students:
Major
Gender Accounting Management Finance Total
Male 100 150 50 300
Female 100 50 50 200
Total 200 200 100 500
a) What is the probability of selecting a female student?
b) What is the probability of selecting finance or accounting major?
c) What is the probability of selecting a female or an accounting major? Which rule of addition did you apply?
d) Are gender and major independent? Why?
e) What is the probability of selecting an accounting major, given that the person selected is a male?
f) Suppose two students are selected randomly to attend a lunch with the president of the university. What is the probability that both of those students are accounting majors?
Click here to see answer by stanbon(26259) |
Question 172151: A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were
3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437
(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence? (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. (Data are from a project by MBA student Henry Scussel.) Tootsie
Click here to see answer by stanbon(26259) |
Question 172165: An industrial process that makes 3-foot sections of plastic pipe produces pipe with an average inside diameter of 1 inch and a SD of 0.05 inch. If you randomly select one piece of pipe what is the probability that its inside diameter will exceed 1.02 inch assuming the population is normal.
Click here to see answer by stanbon(26259) |
Question 172727: During her four years at college, Rose received the following amounts of money at the end of each year from her grandmother. She deposited her money in a saving account paying 6 percent rate of interest. How much money will Rose have on graduation day?
Year $
1 100
2 200
3 300
4 400
Click here to see answer by w1ldc4t(2) |
Question 173091: The inside diameter of metal washers produced by a company are normally distributed with a mean of 0.5 inches and a standard deviation of 0.01 inches. Of all washers produced, 0.8% of the washers are rejected because they are to small for a bolt used to test them. What is the diameter of the bolt used for the test?
I have tried almost every formula and I cannot seem to get this one at all, please help! Thanks
Click here to see answer by stanbon(26259) |
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