Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 581390: Defective
Suppose that a company determines if it will accept a shipment of 15 items by sampling 5 of the items for close inspection. Suppose that 4 of the items in the shipment are defective.
Referring to Defective, find the standard deviation of the number of defective items.
I think the way to do this problem is npq to get the variance and then find the square root to get the standard deviation. (5)(.8)(.2)=.8 then the square root is .8944
Click here to see answer by stanbon(57282)  |
Question 581393: Cans of classic Coke are filled so that the mean is 12.0 ounces with a standard deviation of 0.1 ounces. Find the probability that
a) a single can will have 12.2 or more ounces
b) a sample of 36 cans will have 12.2 or more ounces
c) Explain the difference in the answers for parts a and b
Any help would be awesome.
Thank you
Rae
Click here to see answer by stanbon(57282) |
Question 581394: The mean SAT math reasoning score in 2009 was 515.3 with a standard deviation of 114.1. An educational psychologist believes that students who take at least 4 years of English in high school perform better on the exam. To test the hypothesis, she obtains a random sample of 40 student (with 4 years of English) and their mean score was 540. Test the claim at "alpha" = 0.05.
I am so lost on this one.
Thank you
Click here to see answer by stanbon(57282) |
Question 581465: At a local college, times for running the mile are approximately normally distributed with a mean of 4.5 minutes and a standard deviation of 0.3 minutes. What is the probability that a randomly selected time will be less than 4 minutes?
Thanks again.
Click here to see answer by dfrazzetto(277)  |
Question 581466: Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A's to the top 10% of students and B's to the next 23%. What is the bottom cut-off for a B grade? Round to the nearest whole number.
My answer = 76
Thank you very much!
Click here to see answer by stanbon(57282) |
Question 581464: Which score has the better relative position: a score of 49 on a test for which the mean is 41 and the standard deviation is 8, a score of 5.8 on a test for which the mean is 5 and the standard deviation is 0.7, or a score of 491.6 on a test for which the mean is 467 and the standard deviation is 41?
My answer = A score of 5.8
Thanks...you're the best!
Click here to see answer by stanbon(57282) |
Question 581463: Elizabeth and Ann skate for their college speed skating team. In the last race, Elizabeth skated the 500 meter race in 60 seconds. The average for this race is 65 seconds with a standard deviation of 4.0 seconds. Angela skated the 1,000 meter race in 132 seconds. The average race for this race is 140 seconds with a standard deviation of 10.0 seconds. Find the z-score for each skater. Relatively speaking, which skater had the faster time?
My answer = -1.2, -0.8; Angela faster skater
Thank you.
Click here to see answer by stanbon(57282) |
Question 581461: The table shows the percentage of college students who prefer a given pizza topping.
Cheese: Freshman = 5.19, Sophomore = 7.55, Junior = 11.79, Senior = 10.38
Meat: Freshman = 9.43, Sophomore = 10.38, Junior 7.55, Senior = 5.19
Veggie: Freshman = 7.55, Sophomore = 5.19, Junior = 9.43, Senior = 10.38
What is the probability that a randomly selected student prefers cheese toppings? Round to nearest hundredth.
Thank you.
Click here to see answer by stanbon(57282) |
Question 581451: This are questions from homework from the other week. My professor already gave me the answers but not how to do the work; it is an online statistics class. I have been looking up things. I want to make sure how to do the steps properly. Below are the questions. Thank you so much!
Given a test that is normally distributed with a mean of 30 and a standard deviation of 6, what is the probability that a single score drawn at random will be greater than 34?
If scores are normally distributed with a mean of 85 and a standard deviation of 10, approximately what percentage of the scores are between 60 and 100?
If scores are normally distributed with a mean of 85, and a standard deviation of 10, approximately what percentage of the scores are greater than 80?
If scores are normally distributed with a mean of 85, and a standard deviation of 10, approximately what percentage of the scores are greater than 95?
Click here to see answer by stanbon(57282) |
Question 581441: Dorians score of 572 on the normally distributed verbal portion of the 1996 SAT exam placed him at the seventy third percentile. If the mean on this exam was 505, what was the standard deviation? Please help me with this!
Click here to see answer by stanbon(57282) |
Question 581483: If 20 women and 20 men in his statistics course and one class individual is randomly selected.
1) What is the probability that the individual is a woman?
2) What are the odds of the individual selected is a woman?
3) What are the odds of the individual selected against being a woman?
Click here to see answer by stanbon(57282) |
Question 581478: Find the critical value X˛R corresponding to a sample size of 25 and a confidence level of 99%
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Assuming you want a T-interval:
invT(0.995) = 2.7969
===============================
Cheers,
Stan H.
======================
Click here to see answer by stanbon(57282) |
Question 581439: A national reading test has a mean of 60.3 and a standard deviation of 7.82. The school district in smithville gave the exam to all students in the designated grade. The district average for all students was 69.2. In Miss Browns class , the average was 75.9. A)Based on the national scores what is the z-score for smithville district average score?
B) Based on the national scores, what is the z-score for the average score earned in Miss Browns class?
C)Assume that the distribution of all scores was a normal distribution. Approximately what percent of students in the country scored lower than miss browns class average?
Im not sure if I got A and B correct but my answers were 1.138 and 1.994?! I did not know C... Please help me with this!
Click here to see answer by stanbon(57282) |
Question 581406: Given a level of confidence of 955 and a population standard deviation of 14.
A. what other information is necessary to find the sample size (n).
B. find the maximum error of estimate 9e) if n=78 show work.
Click here to see answer by stanbon(57282) |
Question 581549: A box contains 11 red balls, 9 green balls, and 9 black balls. A sample of 9 is to be picked from the box.
(a) How many samples contain at least 1 red ball?
9966385 samples
(b) How many samples contain exactly 4 red balls and exactly 3 black balls?
997920 samples
(c) How many samples contain exactly 5 green balls or exactly 3 black balls?
I need to figure this last part of the problem out and I know that (C(9,5)*C(20,4))+(C(9,3)*C(20,6))-(C(9,5)*C(9,3)) is the format I need but I can't seem to get the correct answer out of it.
Click here to see answer by stanbon(57282) |
Question 581612: A car dealer will sell you the $16,450 car of your dreams for $3,270 down and payments of $339.70 per month for 48 months. What is the total amount paid for both car and financing? (Round your answer to the nearest cent).
Click here to see answer by stanbon(57282) |
Question 581578: IQ as measured by the Wechsler Adult Intelligence Test, is scaled so that the mean in the population is 100 with a standard deviation of 15. What is the probability of randomly sampling a member out of this population who has an IQ of 120 or greater?
What is the probability of randomly sampling a set of 5 people out of this population who have a mean IQ of 120 or greater.
Click here to see answer by stanbon(57282) |
Question 581557: The mark 'x' of an exam is normally distributed with a mean of 64 and a standard deviation of 8. If 200 students take the exam, how many students would you expect to obtain a mark between 64 and 80?
Thank you so much for your help
Click here to see answer by stanbon(57282) |
Question 581630: Question #1
Find the amount of interest and the monthly payment of the loan. Purchase a car for $42,400 at 2.4% add-on rate for 5 years. (Round your answers to the nearest cent).
My answers were incorrect Interest: $1746
Per month: $394.88
Question #2
find the ending balance in an account that opens with $3,940, earns 9.5% interest compounded monthly, and is held for 10 years. (round your answer to the nearest cent)
My answer was incorrect: $10149
Click here to see answer by jim_thompson5910(28536) |
Question 581758: a computer program consists of two blocks written independently by two different programmers. the first block has an error with probability .2. the second block has an error with probability .3. if the program returns an error, what is probability that there is an error in both blocks?
Click here to see answer by stanbon(57282) |
Question 581733: In developing patient appointment schedules, a medical center wants to estimate the mean time that a staff member spends with each patient. How large a sample should be taken if the desired margin of error is two minutes at a 95% level of confidence? How large a sample should be taken for a 99% level of confidence? Use a planning value for the population standard deviation of eight minutes.
Click here to see answer by stanbon(57282) |
Question 581895: I have a problem with this problem:
The square letter tiles shown below are placed in an empty box. The tiles are equal in size. 2 B tiles,4 N tiles, 3 R tiles, and 1 O tile.
If two tiles are randomly selected without replacement, what is the probability that the first tile will be the letter R and the second tile will be the letter N?
Click here to see answer by jim_thompson5910(28536) |
Question 581900: The mean weekly income of teachers in one state is $390 with a standard deviation of $45. The incomes are approximately normally distributed. What is the probability that a randomly selected teacher earns more than $425 a week?
My answer = 0.215
Thank you!
Click here to see answer by jim_thompson5910(28536) |
Question 581903: The mean clotting time of blood is 7.35 seconds with a standard deviation of 0.35 seconds. The times are approximately normally distributed. What is the probability that a randomly selected blood clotting time will be less than 7 seconds?
My answer = 0.156
Thanks.
Click here to see answer by jim_thompson5910(28536) |
Question 581903: The mean clotting time of blood is 7.35 seconds with a standard deviation of 0.35 seconds. The times are approximately normally distributed. What is the probability that a randomly selected blood clotting time will be less than 7 seconds?
My answer = 0.156
Thanks.
Click here to see answer by solver91311(16872)  |
Question 581917: For the daily lottery game in a lottery, players select three numbers between 0 and 9. A number cannot be selected more than once, so a winning ticket could be, 203 or 302. 222, or 330 is not allowed. Purchasing one ticket allows you to select one set of numbers. How many different outcomes (three digit numbers) are possible?
Click here to see answer by sudhanshu_kmr(1152)  |
Question 581921: Sally's has a business that was open for 4 days. The number of customers on each day were 7, 11, 9, 4. Assume that the samples of size 2 are randomly selected with replacement from this population of 4 values. The first sample selected is 11,9. What is the mean of the sampling distribution of means?
Click here to see answer by stanbon(57282) |
Question 581943: A company assigns an order number to all of its internet orders. The order number consiss of two letters (A to Z) followed by 4 distinct (each from 0-9 with no numbers repeated). An example would be AF294. How many different order numbers can the company assign? I concerned with the formula used also?
Click here to see answer by stanbon(57282) |
Question 581980: The equation used to predict the total body weight (in pounds) of a female athelit from a certian high school is y (greater than symbol over the y) =neg 115+3.04x(one below x) +1.26x (2 below x) where x(one below x) is the females athelites height (in inches) and x( two below the x) is the female athelites percent body fat. Use the motiple regression equation to predict the total body weight for the female athlete who is 68 inches talland has 23% body fat.
The predicted total body weight for the female athlete who is 68 inches talland has 23% body fat is _____ pounds. (Round to the nearest tenth as needed)
Click here to see answer by jim_thompson5910(28536) |
Question 581980: The equation used to predict the total body weight (in pounds) of a female athelit from a certian high school is y (greater than symbol over the y) =neg 115+3.04x(one below x) +1.26x (2 below x) where x(one below x) is the females athelites height (in inches) and x( two below the x) is the female athelites percent body fat. Use the motiple regression equation to predict the total body weight for the female athlete who is 68 inches talland has 23% body fat.
The predicted total body weight for the female athlete who is 68 inches talland has 23% body fat is _____ pounds. (Round to the nearest tenth as needed)
Click here to see answer by stanbon(57282) |
Question 581990: Forty moviegoers were surveyed as they left the movie theater. They were asked the rating of the movie they just say. The resulted are shown below.
Movie Type Number
G 4
PG 12
PG13 15
R 9
If you randomly selected an individual from this group, what is the probability that the individual saw a movie that was rated PG? If you randomly selected an individual from this group, what is the probablity the the individual saw a movie that was rated something other than PG? Formula?
Click here to see answer by stanbon(57282) |
Question 581990: Forty moviegoers were surveyed as they left the movie theater. They were asked the rating of the movie they just say. The resulted are shown below.
Movie Type Number
G 4
PG 12
PG13 15
R 9
If you randomly selected an individual from this group, what is the probability that the individual saw a movie that was rated PG? If you randomly selected an individual from this group, what is the probablity the the individual saw a movie that was rated something other than PG? Formula?
Click here to see answer by jim_thompson5910(28536) |
Question 581985: I need Help Please!!!!!!!!!!
T-Tests
•Choose and calculate the appropriate analysis to compare the anxiety levels of the participants in the CBT treatment to those in the psychodynamic treatment using posttest scores only.
•Choose and calculate the appropriate analysis to compare the anxiety levels of participants in the CBT group only at pre- and posttest.
Here is the information in order to do the calculations:
SubjectID.....Pre-RCMAS....Post-RCMAS
1.................23............8
2.................22............15
4.................26............11
5.................20............15
7.................25............4
8.................22............14
Okay I have to use either independent t-tests or paired t-tests or one sample t-test in order to complete this assignment. I have to show all work inlcuding all calculations. The Subject ID is not important. I need help I have no idea on how to to this please help.
Click here to see answer by stanbon(57282) |
Question 581994: A survey of incoming freshmen at a college revealed that 35% had an IPad,85% had a Facebook account, and 25% had both. What is the probability that a selected freshman has an IPad or a Facebook account? Formula?
Are the two events ( having an IPad, having a Facebook account) mutually exclusive? Explain?
Based on the answer in part a, What is the probabilty that a selected freshmen did not have an IPad and did not have a Facebook account?
Click here to see answer by stanbon(57282) |
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