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

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 Algebra: Probability and statistics Solvers Lessons Answers archive Quiz In Depth

 Question 172989: A) What is the 90% confidence interval for the variance of exam scores for 28 algebra students, if the standard deviation of their last exam was 12.7? B)A lawyer researched the average number of years served by 49 different justices on the Supreme Court. The average number of years served was 14.9 years with a standard deviation of 8.6 years. What is the 95% confidence interval for the average number of years served by all Supreme Court justices? C)A high school math teacher thinks the variance on his next math test should be 125. When his class of 27 students takes the next test, they have a standard deviation of 133. The test value for this data would be 27.664. Click here to see answer by stanbon(57347)

 Question 174453: what number should be added to the following set of data so that the mean,median,and mode will become the same number ? 91,93,93,95,95,98,100 Click here to see answer by checkley77(12569)
 Question 174453: what number should be added to the following set of data so that the mean,median,and mode will become the same number ? 91,93,93,95,95,98,100 Click here to see answer by Edwin McCravy(8909)

 Question 173960: An exeriment to measure the effect of giving growth hormones to girls affected by Turner's Syndrome was carried out recently in Vancouver. All 34 girls in the study were given the growth hormone and their heights were measured at the time the hormone was given and again one year later. No measurements were made on their final adult heights. Which of the following is not a problem with this experiment: (a) There was no blinding. (b) There was no control group. (c) Nonresponse bias. (d) There was insufficient attentionto the placebo effect. (e) Because final heights were not measured, it is impossible to tell if the hormone affected final height or only accelerated growth and made no difference to final height. Click here to see answer by Alan3354(30993)

 Question 174883: Suppose that a researcher is interested in estimating the mean systolic blood pressure, , of executives of major corporations. He plans to use the blood pressures of a random sample of executives of major corporations to estimate . Assuming that the standard deviation of the population of systolic blood pressures of executives of major corporations is mm Hg, what is the minimum sample size needed for the researcher to be confident that his estimate is within mm Hg of ? Click here to see answer by stanbon(57347)

 Question 172541: 5 CHEVROLETS ARE CRASH TESTED TO FIND OUT THEIR MEAN REPAIR COST. IT WAS FOUND THAT THE MEAN REPAIR COST OF THIS SMALL SAMPLE WAS \$1706 WITH AN S.D OF \$830. cONSTRUCT A 90% CONFIDENCE INTERVAL FOR THE MEAN REPAIR COST IN ALL SUCH VEHICLE COLLISIONS. Click here to see answer by stanbon(57347)

 Question 175213: How do I solve the quotient of b^3+4b^2-3b+126 over b+7? Click here to see answer by Mathtut(3670)

 Question 175214: How do I find the sum of the first 10 posivtive integers? Click here to see answer by Mathtut(3670)
 Question 175214: How do I find the sum of the first 10 posivtive integers? Click here to see answer by solver91311(16885)

 Question 175216: The first two terms of a geometric sequence are a(base1)=1/3 and a(base2)=1/6. How do I find a(base8) the eighth term? Click here to see answer by Edwin McCravy(8909)

 Question 175215: How do I solve this problem? the first two terms of an arithmetic sequence are a(base1)=2 and a(base2)=4. what is the a(base10)? Click here to see answer by gonzo(654)

 Question 175211: What is the remainder when 3t^2+5t-7 is divided by t-5? Click here to see answer by gonzo(654)

 Question 175302: 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? Click here to see answer by stanbon(57347)

 Question 175479: Recently, students in a marketing research class were interested in the driving behavior of students. Specifically, the marketing students were interested if exceeding the speed limit was related to gender. They collected the following responses from 100 randomly selected students: Speeds Does not speed Males 40 25 Females 10 25 1. The appropriate test to analyze the relationship between gender and education is: A. regression analysis B. Analysis of variance C. Contingency table analysis D. Goodness-of-fit 2. The null hypothesis for the analysis is: A. There is no relationship between gender and speeding. B. The correlation between gender and speeding is zero. C. As gender increases, speeding increases. D. The mean of gender equals the mean of speeding. 3. The degrees of freedom for the analysis is: A. 1 B. 2 C. 3 D. 4 4. Using 0.05 as the significance level, what is the critical value for the test statistic? A. 9.488 B. 5.991 C. 7.815 D. 3.841 5. What is the value of the test statistic? A. 100 B. 9.89 C. 50 D. 4.94 6. Based on the analysis, what can be concluded? A. Gender and speeding are correlated. B. Gender and speeding are not related. C. Gender and speeding are related. D. No conclusion is possible. Click here to see answer by stanbon(57347)

 Question 175565: 10.52 One group of accounting students took a distance learning class, while another group took the same course in a traditional classroom. At α = .10, is there a significant difference in the mean scores listed below? (a) State the hypotheses. (b) State the decision rule and sketch it. (c) Find the test statistic. (d) Make a decision. (e) Use Excel to find the p-value and interpret it. Exam Scores for Accounting Students Statistic Distance Classroom Mean scores ¯x1 = 9.1 ¯x2 = 10.3 Sample std. dev. s1 = 2.4 s2 = 2.5 Number of students n1 = 20 n2 = 20 Click here to see answer by stanbon(57347)

 Question 175509: 14. The following table shows the adjustment to civilian life and place of residence. *SORRY.. this is the only way i could reformat the "table" for it to make sense. The actual table was not lining up. (Residence After Release From Prison) Adjustment to Civilian Life = Outstanding (Hometown) = 27 (Not hometown)= 13 Total = 40 (Residence After Release From Prison) Adjustment to Civilian Life = Good (Hometown) = 35 (Not hometown)= 15 Total = 50 (Residence After Release From Prison) Adjustment to Civilian Life = Fair (Hometown) = 33 (Not hometown)= 27 Total = 60 (Residence After Release From Prison) Adjustment to Civilian Life = Unsatisfactory (Hometown) = 25 (Not hometown)= 25 Total = 50 What is the critical value for this contingency table at the 0.01 level of significance? A) 9.488 B) 2.070 C) 11.345 D) 13.277 E) None of the above Click here to see answer by stanbon(57347)

 Question 175517: The educational level and the social activity of a sample of executives follow. Education Social Activity=Above Average College = 30 High School = 20 Grade School = 10 Education Social Activity = Average College = 20 High School = 40 Grade School = 50 Education Social Activity=Below Average College = 10 High School = 90 Grade School = 130 What does the expected frequency for the "above average" social activity and "high school" education equal? A) 9.50 B) 60.00 C) 22.50 D) 28.50 E) None of the above Click here to see answer by stanbon(57347)

 Question 175483: A distributor of personal computers has five locations in the city. The sales in units for the first quarter of the year were as follows: Location - Observed Sales (Units) North Side - 70 Pleasantway - 75 Southwyck - 70 I-90 -50 Venice Avenue - 35 TOTAL = 300 What is the critical value at the 0.01 level of risk? A) 7.779 B) 15.033 C) 13.277 D) 5.412 E) None of the above Click here to see answer by stanbon(57347)

 Question 175638: 2. You will be asked to identify the type of variable (quantitative or qualitative) in each of the following situations. a. Whether or not an individual would be willing to spend 10 percent more for energy from a non-polluting source. b. The amount an individual user pays for internet access on a monthly basis. I chose quantitative for both a and b. Is that correct? Click here to see answer by vleith(2825)

 Question 175646: You will be asked to determine whether each of the following quantitative variables is discrete or continuous. A.) The amount of money the CEO is paid. B.) The number of staff members who report to the CEO. For A.) I choose discrete and for B.) I chose continuous. Are they correct? Click here to see answer by user_dude2008(1861)

 Question 175661: Diana has a box containing 6 blue, 8 red, 5 purple, 9 green, and 2 clear marbles that are all the same size and shape. What is the probability of randomly choosing a clear marble on the first pick; replacing it, and then randomly choosing a purple marble on the second pick? Click here to see answer by checkley75(3666)
 Question 175661: Diana has a box containing 6 blue, 8 red, 5 purple, 9 green, and 2 clear marbles that are all the same size and shape. What is the probability of randomly choosing a clear marble on the first pick; replacing it, and then randomly choosing a purple marble on the second pick? Click here to see answer by jim_thompson5910(28595)
 Question 175661: Diana has a box containing 6 blue, 8 red, 5 purple, 9 green, and 2 clear marbles that are all the same size and shape. What is the probability of randomly choosing a clear marble on the first pick; replacing it, and then randomly choosing a purple marble on the second pick? Click here to see answer by gonzo(654)

 Question 175659: How do you make a tree diagram for rolling two number cubes? Including the sum of each outcome. Click here to see answer by Fombitz(13828)

 Question 175705: The records of a casualty insurance company show that, in the past, its clients have had a mean of auto accidents per day with a variance of 1.8 . The actuaries of the company claim that the variance of 0.0016 the number of accidents per day is no longer equal to 0.0016 . Suppose that we want to carry out a hypothesis test to see if there is support for the actuaries' claim. State the null hypothesis Ho and the alternative hypothesis Hi that we would use for this test. Click here to see answer by stanbon(57347)

 Question 175765: 1. Find the number of permutations in the word GEOMETRY. 2. In how many ways can 12 books be displayed on a shelf if 12 books are available. Click here to see answer by stanbon(57347)

 Question 175812: I'm stumped on 2 word problems dealing with probability. Can someone please help me???? Here they are: 1. Suppose a contest offers \$1,000 to the person who can guess the winning four digit number. How many possibilities are there? 2. There are 10 women and 8 men in a club. How many different committees of 6 people can be selected from the group if equal numbers of men and women are to be on the committee? TIA for your help! Andrew Click here to see answer by stanbon(57347)

 Question 175855: A TV special said there is a 10 per cent incidence of sexually transmitted disease (STD) among all U.S. teens. A reporter for the Rockville Bugle, looking for a story, surveyed 260 randomly chosen teenagers, and found that 39 had been to a clinic for STD treatment. Use a right-tail test at α = .05. The test statistic is The critical value is The p-value is Click here to see answer by stanbon(57347)

 Question 175853: In determining the p-value for reporting the study's findings, which of the following is true? Click here to see answer by stanbon(57347)

 Question 175838: To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack kept track of the order in which papers were handed in. The first 25 papers showed a mean score of 77.1 with a standard deviation of 19.6, while the last 24 papers handed in showed a mean score of 69.3 with a standard deviation of 24.9. Is this a significant difference at α = .05? (a) State the hypotheses for a right-tailed test. (b) Obtain a test statistic and p-value assuming equal variances. Interpret these results. (c) Is the difference in mean scores large enough to be important? (d) Is it reasonable to assume equal variances? (e) Carry out a formal test for equal variances at α = .05, showing all steps clearly. Click here to see answer by stanbon(57347)

 Question 175907: Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped kernels were counted. There were 86. (a) Construct a 90 percent confidence interval for the proportion of all kernels that would not pop. (b) Check the normality assumption (c) Try the Very Quick Rule. Does it work well here? Why, or why not? (d) Why might this sample not be typical? Click here to see answer by stanbon(57347)

 Question 175906: 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 Click here to see answer by stanbon(57347)

 Question 175836: Does lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas study, researchers gave lovastatin to 2,325 people and an inactive substitute to 2,081 people (average age 58). After 5 years, 57 of the lovastatin group had suffered a heart attack, compared with 97 for the inactive pill. (a) State the appropriate hypotheses. (b) Obtain a test statistic and p-value. Interpret the results at α = .01. (c) Is normality assured? (d) Is the difference large enough to be important? (e) What else would medical researchers need to know before Is the difference large enough to be important? (e) What else would medical researchers need to know before prescribing this drug widely? Click here to see answer by stanbon(57347)

 Question 175835: In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents, while the fleet of yellow fire trucks made 135,035 runs and had 4 accidents. At α = .01, did the yellow fire trucks have a significantly lower accident rate? (a) State the hypotheses. (b) State the decision rule and sketch it. (c) Find the sample proportions and z test statistic. (d) Make a decision. (e) Find the p-value and interpret it. (f) If statistically significant, do you think the difference is large enough to be important? If so, to whom, and why? (g) Is the normality assumption fulfilled? Explain. Click here to see answer by stanbon(57347)

 Question 176064: Long-term history has shown that 65% of all elected offices in a rural county have been won by Republican candidates. This year there are 5 offices up for public election in the county Let r be the number of public offices won by Republicans. a) Find P(r) for r=0,1,2,3,4, and 5 b) Make a histogram for the r probability distribution. c) What is the expected number of Republicans who will win office in the coming election? d) What is the standard deviation of r? Click here to see answer by stanbon(57347)

 Question 176170: Question: A heating and ventilation engineer purchases four 1m radiators and three 1.5m radiators at a cost of £159 for a project. In addition he purchases five 1m radiators and two 1.5m radiators at a cost of £134. Determine the cost of both types of radiator. Click here to see answer by EMStelley(187)
 Question 176170: Question: A heating and ventilation engineer purchases four 1m radiators and three 1.5m radiators at a cost of £159 for a project. In addition he purchases five 1m radiators and two 1.5m radiators at a cost of £134. Determine the cost of both types of radiator. Click here to see answer by Mathtut(3670)

 Question 176173: Suppose there are 10 items on a true-false test. The person taking the test does not read the questions; he just answers each question randomly. What is the probability of his guessing ALL answers correctly? I have to come up with a formula type answer for this, but know that he has a 50/50 chance of answering the questions correctly or at least a 1% chance. Heeelllp! TIA Click here to see answer by Mathtut(3670)

 Question 176071: In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with the results shown below. Research question: Are the mean crash damages the same for these three vehicles? Crash1 Crash Damage (\$) Goliath Varmint Weasel 1,600 1,290 1,090 760 1,400 2,100 880 1,390 1,830 1,950 1,850 1,250 1,220 950 1,920 Click here to see answer by stanbon(57347)

 Question 176197: The mean SAT score in mathematics is 508 . The founders of a nationwide SAT preparation course claim that graduates of the course score higher, on average, than the national mean. Suppose that the founders of the course want to carry out a hypothesis test to see if their claim has merit. State the null hypothesis Ho and the alternative hypothesis H1 that they would use. Quick Help please Click here to see answer by MathTherapy(1424)

 Question 176476: arrange these # in order from least to greatest : 25%, 0.5, 3/5, 0.45, 4/20, 65% flip a coin and roll a die find P ( tails and mutiple of 3) Click here to see answer by Mathtut(3670)

 Question 176335: A sample of 25 concession stand purchases at the October 22 matinee of Bride of Chucky showed a mean purchase of \$5.29 with a standard deviation of \$3.02. For the October 26 evening showing of the same movie, for a sample of 25 purchases the mean was \$5.12 with a standard deviation of \$2.14. The means appear to be very close, but not the variances. At α = .05, is there a difference in variances? Show all steps clearly, including an illustration of the decision rule. (Data are from a project by statistics students Kim Dyer, Amy Pease, and Lyndsey Smith. Click here to see answer by stanbon(57347)

 Question 176503: Which of the following statements is correct? For a given level of significance, the critical value of Student's t increases as n increases. A test statistic of t = 2.131 with d.f. = 15 leads to a clear-cut decision in a two-tailed test where α = .05. It is harder to reject the null hypothesis when conducting a two-tailed test rather than a one-tailed test. If we desire α = 0.10 then a p-value of 0.13 would lead us to reject the null hypothesis. Click here to see answer by stanbon(57347)

 Question 176540: At a certain non-profit organization, % of employees are college graduates and % of employees have more than ten years of experience. If % of the organization's employees are either college graduates or have more than ten years of experience (or both), what is the probability that a randomly selected employee will have more than ten years of experience and be a college graduate? Click here to see answer by stanbon(57347)

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