# Questions on Algebra: Probability and statistics answered by real tutors!

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 Question 264918: Two standard six-sided dice are rolled. The probability that the sum of the two dice is 9 or larger is A.1/3 B.1/4 C. 1/6 D. 1/9 E. 5/18 Click here to see answer by stanbon(60778)

 Question 264890: Three integers are randomly selected without replacement from the set { 1,2,3,5,6,7}. What is the probability that the mean of the values chosen is less than, but not equal to, 5? Click here to see answer by stanbon(60778)

 Question 264759: A survey of 100 companies reveals that 15 private and 30 public companies are planning to restart hiring, while 40 private and 15 public companies do not plan on restarting hiring. What is the probability that a company is both private and does not plan to restart hiring? Click here to see answer by stanbon(60778)

 Question 264960: 15) A test for equality of two variances has sample sizes n1 = 13 and n2 = 10. The degrees of freedom for the test are A. 21. B. 13 and 10. C. 12 and 9. D. 26. Click here to see answer by stanbon(60778)

 Question 264979: Two standard dice are rolled. Let A be the event that the first die lands on a number less than 4. Let B be the event that the second die lands on 5. Which of the following are true? A. P(B) = B. P(A and B) = C. P(A and B) = D. P(A ) = Click here to see answer by stanbon(60778)

 Question 264959: 14) A pooled proportion estimate may be used to calculate the test statistic for a test of the equality of proportions when the A. populations are normally distributed. B. samples are independently drawn from the populations. C. null hypothesis states that the two population proportions are equal. D. sample sizes are small. Click here to see answer by stanbon(60778)

 Question 264803: Suppose a school had 600 students. Math teachers gave A's to 20% of the students. English teachers gave A's to 15% of the students. 8% received A's in both math and english. What percent received an A in at least one of the 2 subjects? How many students received an A in at least one of the two subjects? Click here to see answer by ankor@dixie-net.com(16525)

 Question 230201: A machine is set to fill the small size packages of M&M candies with 56 candies per bag. A sample revealed: 3 bags of 56, 2 bags of 57, 1 bag of 55 and 2 bags of 58. How many degrees of freedom are there? A. 9 B. 1 C. 8 D. 7 Click here to see answer by Brownjewel(1)

 Question 265147: there is a license plate with 7 spots. the first 4 are capital letters and the last 3 are digits. what is the probability that the first 3 letters will spell "wow"? Click here to see answer by stanbon(60778)

 Question 265165: The mean gross annual incomes of certified tack welders are normally distributed with the man of \$20,000 and a standard deviation of \$2,000. The shop building association wishes to find out whether their tack welders earn more of less than \$20,000 annually. The alternate hypothesis is that the mean is not \$20,000. what is the alternate hypothesis? Click here to see answer by beachboyz(1)
 Question 265165: The mean gross annual incomes of certified tack welders are normally distributed with the man of \$20,000 and a standard deviation of \$2,000. The shop building association wishes to find out whether their tack welders earn more of less than \$20,000 annually. The alternate hypothesis is that the mean is not \$20,000. what is the alternate hypothesis? Click here to see answer by stanbon(60778)

 Question 265175: The telephone extentions at a company uses 4 digits. How many extensions are possible is there are no restrictions? Click here to see answer by stanbon(60778)

 Question 265192: In a certain class, 40% of students are seniors, 15% of the students are failing, and 10% are seniors who are failing. What is the conditional probability that a student is failing given that he/she is a senior? Click here to see answer by stanbon(60778)

 Question 265191: In a certain class, 40% of the students are seniors, 15% are failing, and 10% are seniors who are failing. What is the probability that a randomly chosen student is failing? Click here to see answer by stanbon(60778)

 Question 265262: All airplanes in the United States have identification letters that start with the letter N. Private planes have the letter N followed by four numbers followed by another letter. The letters I, O, and Z are never used. How many possible private aircraft identification numbers are there? Click here to see answer by dabanfield(803)

 Question 265355: An ordinary (fair) die is a cube with the numbers through on the sides (represented by painted spots). Imagine that such a die is rolled twice in succession and that the face values of the two rolls are added together. This sum is recorded as the outcome of a single trial of a random experiment. Compute the probability of each of the following events: Event : The sum is greater than . Event : The sum is divisible by . Click here to see answer by stanbon(60778)

 Question 265265: A school has scheduled three volleyball games, two soccer games, and four basketball games. You have a ticket allowing you to attend three of the games. In how many ways can you go to two basketball games and one of the other events?(including another basketball game) Clearly show how you came to your conclusion. Click here to see answer by stanbon(60778)

 Question 265452: A firm is studying the production times for two production methods. The firm is satisfied with production method A and is prepared to continue using it if the mean delivery time is the same as or less than for production method B. However, if the firm finds that the mean delivery time for method B is less than that for method A, it will begin using method B. a. What are the null and alternative hypotheses? Assume that independent samples show the following delivery time characteristics for the two production methods. Method A Method B n=40,x'=13.5,s2=4 n=45 x'=15 s1=4 b. With  = .02, what is your conclusion for the hypotheses from part a? (Show your work.) c.c. What action do you recommend regarding selection of a production method? Click here to see answer by stanbon(60778)

 Question 265376: What are the probabilities that a student will receive an A, B, C, D, and F in a class? (using standard grading scale: A=90-100, B=80-89, C=70-79, D=60-69, F=0-59)? Thank you!! Click here to see answer by stanbon(60778)

 Question 265278: In 2004, 57.2% of all enrolled college students were female. Choose one enrolled student at random. What is the probability that the student was male? Thanks! Click here to see answer by stanbon(60778)

 Question 265552: I am having a difficult time understanding this problem. Can someone please help? A researcher is interested in estimating the proportion of voters who favor a tax on e-commerce. In a sample of 250 people she finds that 36 favor such a tax. a. Find a 95% confidence interval for the true population proportion of voters who favor such a tax. b. Find a 99% confidence interval for the true population proportion of voters who favor such a tax. Click here to see answer by stanbon(60778)

 Question 265571: Can someone please answer this and help me understand how to calculate? Thank you. According to a recent poll, 16.2% of credit cardholders in the United States have used their credit card to make a purchase on the internet. You will be asked to identify how large a sample should be taken if the true proportion is to be estimated to within 1.5% at the 95% reliability level? You may use the sample proportion in the calculation of the sample size. Click here to see answer by stanbon(60778)

 Question 265610: My friend works on computers his average time is 4 hours with a 1 hour standard deviation 1 What is the chance that he works on a computer from his average to 5 hours 2 What is the chance that he works on a computer from 3 hours to his average 3 What is the chance that he works on a computer from 3 hours to 5 hours 4 What is the chance that he works on a compute more than 5 hours Click here to see answer by stanbon(60778)

 Question 265607: Children Watching TV. The A.C. Nielsen Company reports in te Nielsen Report on Television that te mean weekly television viewing time for children aged 2-11 years is 24.50 hours. Assume that the weekly television viewing times of such children are normally distributed with a standard deviation of 6.23 hours and apply the 68.26-95.44-99.74 rule to fill in the blanks. a. 68.26% of all such children watch between ________ and _________ hours of TV per week. b. 95.44% of all such children watch between ________ and __________ hours of TV per week c. 99.74% of all such children watch between ________ and ___________ hours of TV per week. Click here to see answer by stanbon(60778)

 Question 265604: Metastatic Carcinoid Tumors. A study of sizes of metastatic carcinoid tumors in the heart was conducted by U. Pandya et al. and published as the article, “Metastatic Carcinoid Tumor to the heart: Echocardiographic-Pathologic Study of 11 Patients” Based on that study, we assume that lengths of metastatic carcinoid tumors in the heart are normally distributed with mean 1.8cm and standard deviation 0.5cm. Find the percentage of metastatic carcinoid tumors in the heart that a. are between 1 cm and 2 cm long. b. Exceed 3 cm in length Click here to see answer by stanbon(60778)

 Question 265602: given a population with these parameters: Mu=62 and sigma =8 what is the probability of randomly selected score being between 56 and 78. Click here to see answer by stanbon(60778)

 Question 265581: Given the following situation, how would you use Megastat to test whether the two population means are different? Please identify the two populations, outline the process for the test and, if necessary, including the output from Megastat to explain your approach. What assumption do you need to check to make sure that the analysis is valid? "A random sample of 100 pencils produced by assembly line A was inspected in a pencil factory. It was found that the average length is 13.5 cm and the sample standard deviation is 1 cm Another random sample of 80 pencils from assembly line B in the same factory give an average length of 14.26 cm and sample standard deviation of 1.2 cm. Can we conclude that the average length of pencils produced by the two assembly lines are different at the 5% level of significance?" Click here to see answer by stanbon(60778)

 Question 265569: Can anyone help me I been trying to dothis for a couple of days now!!!!!!!!!!!!!! A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 95% confident that her estimate is correct. If the standard deviation is 4.8, how large a sample is needed to get the desired information to be accurate within 0.70 decibels? Show all work Click here to see answer by stanbon(60778)

 Question 265566: Help me please. I am struggling with this. A football coach randomly selected ten players and timed how long each player took to perform a certain drill. The times (in minutes) were: 11 11 7 6 10 6 10 15 12 13 Assuming the population of times to complete the drill is known to be normally distributed, create a 95% confidence interval estimate for Mu, the mean amount of time for all players to complete the drill. Identify x-bar, s, alpha, df, t, E and the confidence interval. Click here to see answer by stanbon(60778)

 Question 265568: Can someone please help me understand this question? The Bide-a-While efficiency hotel, which caters to business workers who stay for extended periods of time (weeks or months), offers room service. The marketing director is interested in trying to determine whether or not she can advertise “room service in under 30 minutes, or the order is free”. You will be asked to identify how many delivery times she should sample to estimate the true mean delivery time to within 5 minutes at the 90% reliability level? Assume that the standard deviation for the delivery times is 18.2 minutes. Click here to see answer by stanbon(60778)

 Question 265560: Can someone please help me understand this question? A 99% confidence interval (in inches) for the mean height of a population is 65.44 < μ < 66.96. This result is based on a sample size of 144. If the confidence interval 65.65 < μ < 66.75 is obtained from the same sample data, what is the degree of confidence? a. You will first need to find the sample mean and sample standard deviation based on the confidence interval given. b. Use the value you found in part a to determine the degree of confidence for the interval 65.65 < μ < 66.75 is based on. Click here to see answer by stanbon(60778)

 Question 265773: a bag contains 3 quarters and 5 dimes. another bag contains 12 pennies and 8 nickels. one coin is chosen from each bag without looking. find the probability of each event Click here to see answer by Edwin McCravy(9717)

 Question 265805: Eight students are chosen at random from a group of twenty of which Alex, Beth and Fraser are a part. What is the probability that Alex, Beth and Fraser are all among the chosen? I have tried the following: 8C3/18C10 = 0.00128 which seems WAY too small a probability. Any thoughts? Click here to see answer by stanbon(60778)
 Question 265805: Eight students are chosen at random from a group of twenty of which Alex, Beth and Fraser are a part. What is the probability that Alex, Beth and Fraser are all among the chosen? I have tried the following: 8C3/18C10 = 0.00128 which seems WAY too small a probability. Any thoughts? Click here to see answer by Edwin McCravy(9717)

 Question 265867: If five cards are selected from a standard deck of 52 cards, what is the probability that the cards are all red? Please help. Thank you. Click here to see answer by Edwin McCravy(9717)

 Question 265891: A production process produces an item. On average, 15% of all items produced are defective. Each item is inspected before being shipped, and the inspector misclassifies an item 10% of the time. What proportion of the items will be "classified as good?" What is the probability that an item is defective given that it was classified as good? Thanks! Click here to see answer by stanbon(60778)

 Question 265871: Question: I have 12 textbooks to arrange on a bookshelf. 5 of them are English textbooks and I would like to arrange the books so that at least two of the English textbooks are adjacent to one another. How many different arrangements are possible? This is how far I have gotten: (# of ways that all are touching) - (# of ways that none are touching) (5!)(7!)(2!) - ???? If I am on the right track... how do I figure out the (# of ways that none are touching)? Click here to see answer by stanbon(60778)

 Question 265870: On a test, a student must answer any 7 of the first 10 questions and any 5 of the second 8 questions. In how many ways can this be done? Please help. Thank you. Click here to see answer by stanbon(60778)

 Question 265967: Create a bell shaped graph for the three solutions a.68.26% of all such children watch between 18.24 and 30.57 hours of TV per week b. 95.44% of all such children watch between 24.5-2*6.23 and 24.5+2*6.23 hours of TV per week c. 99.74% of all such children watch between 24.5-3*6.23 and 24.5+3*6.23 hours of TV per week Click here to see answer by stanbon(60778)

 Question 265995: 11) The standard error of the sample mean is equal to 5 when n=25. If the sample size increases by a factor of four, who will the standard error change? A. It will double. B. It will be cut to ¼ of 5. C. It will quadruple. D. It will be cut in half. Click here to see answer by stanbon(60778)

 Question 265993: 10) The use of the Student’s t distribution requires which of the following assumptions? A. The sample size is greater than 30. B. The population is normal. C. The sample is drawn from a positively skewed distribution. D. The population variance is known. Click here to see answer by stanbon(60778)

 Question 265992: 9) 100 women were polled and 60 reported successfully communicating an automobile problem to an auto repairman. A sample of 150 men had 95 reporting the same success. The value of the test statistic for a test of the equality of proportions is A. -0.5319. B. -0.419. C. 0.2702. D. 0.7293. Click here to see answer by stanbon(60778)

 Question 266023: Determine the correct decision (Reject Jo, or Fail to Reject Ho) for each of the following tests of hypotheses. I have tried to get these and I am not sure what but the formulas are not coming back with a good response for me to make a determination. A hypothesis test at the 0.05 level of significance with a p-value for the sample of 0.105. A hypothesis test at the 0.025 level of significance with a p-value for the sample of 0.002. A two-tailed hypothesis test at the 0.05 level of significance where the initial probability calculated for the test statistic is 0.035. A two-tailed hypothesis test with critical values of +/- 2.33 and a test statistic for the sample of -2.56. A one tailed hypothesis test with a critical value of 2.306 and a test statistic for the sample of 1.652. A one tailed hypothesis test with a critical value of -1.796 and a test statistic for the sample of -.843 Click here to see answer by stanbon(60778)

 Question 266076: A menu has 3 choices for salad, six main dishes, and four desserts. How many different meals are available if you select a salad, a main dish, and a dessert. Click here to see answer by stanbon(60778)

 Question 266112: The call letters of a radio station must have 4 letters. The first letter must be a K or a W. How many different station call letters can be made if repetitions are not allowed? If repetitions are allowed? Thanks! Click here to see answer by Alan3354(34678)