# 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 521400: there are 5 red marbles and 10 green marbles in a bag.if a marble is picked at ramdom,find the probability that the marble is red and green Click here to see answer by Edwin McCravy(8999)

 Question 521469: A poll for the presidential campaign samples 491 potential voters in June. A primary purpose of the poll was to obtain an estimate of the proportion of potential voters who favored each candidate. Assume a planning value of p* = 0.50 and a 95% confidence level. a. For p* = 0.50, what was the planned margin of error for the June poll? (Without calculation process, no credit) b. closer to the November election, better precision and smaller margins of error are desired. Assume the following margins of error are requested for surveys to be conducted during the presidential campaign. Compute the recommended samples size for each survey. (Without calculation process, no credit) Survey Margin of Error September 0.04 October 0.03 Early November 0.02 Pre-Election Day 0.01 Click here to see answer by stanbon(57984)

 Question 521459: A clinical trial is planned to compare an experimental medication designed to lower blood pressure to a placebo. Before starting the trial, a pilot study is conducted involving 10 participants. The objective of the study is to asses how systolic blood pressure changes untreated over time. Systolic blood pressure are measured at baseline and again 4 weeks later. Compute a 95% confidence interval for the mean difference in blood pressure over 4 weeks. Baseline 120 145 130 160 152 143 126 121 115 135 4 weeks 122 142 135 158 155 140 130 120 124 130 Click here to see answer by stanbon(57984)

 Question 522087: Four Students sit a typing test. The probability that Anna passes the test is 1/2 The probablity that Boris passes the test is 4/9 Calulate the probabilty that both Anna and Boris pass the test. Give the answer in its simplest form? Click here to see answer by stanbon(57984)

 Question 522062: A coin is tossed 300 times. What is the probability that heads will appear more than 140 times & less than 150 times? Click here to see answer by stanbon(57984)

 Question 522060: In a certain group of computer personnel, 65% have insufficient knowledge of hardware, 45% have inadequate idea of software & 70% are in either one or both of the two categories. What is the percentage of people who do not know software among those who have a sufficient knowledge of hardware? Click here to see answer by stanbon(57984)

 Question 522031: How many different ways can 9 voters be ordered from first to last? the formula we use is 2^n here n=9 so simply the answer is 512 Click here to see answer by shyfaiza17(5)

 Question 522208: blood pressure readings have a mean of 121 and a standard deviation of 15. Find the percentage of people with blood pressure readings above 136 Click here to see answer by stanbon(57984)

 Question 522192: A die is rolled 360 times. Find the mean, variance, and standard deviation of the number of 4s that will be rolled? Click here to see answer by stanbon(57984)

 Question 522174: Of the 106 first-degree murder cases from 2002 through the first half of 2004 in a certain superior court, 6 cases were thrown out of the system, 65 cases were plea-bargained, and 35 cases went to trial. What is the probability that a case selected at random has the following outcomes? (Round your answers to three decimal places.) (a) settled through plea bargaining (b) went to trial Click here to see answer by stanbon(57984)

 Question 522173: A study conducted by the Corrections Department of a certain state revealed that 164,002 people out of a total adult population of 1,770,000 were under correctional supervision (on probation, parole, or in jail). What is the probability that a person selected at random from the adult population in that state is under correctional supervision? (Round your answer to four decimal places.) Click here to see answer by stanbon(57984)

 Question 522150: random sample of 200 measurements give a mean of 50 and standard deviation of 9. at 5% level of significance, test the hypothesis that the population mean is 52. Click here to see answer by stanbon(57984)

 Question 522105: Find the z-scores for which 20% of the distribution’s area lies between -z and z. A. -0.719, 0.719 B. -0.253, 0.253 C. -0.528, 0.528 D. -0.842, 0.842 Click here to see answer by stanbon(57984)

 Question 522235: A pair of dice is rolled. What is the probability of each of the following? (Round your answers to three decimal places.) (a) the sum of the numbers shown uppermost is less than 7 Click here to see answer by stanbon(57984)

 Question 522264: The appropriate decision rule for a one-tailed test, lower tail critical, at the .05 level of significance, is to reject if a. z ≤ -1.65. b. z ≥ -1.65. c. z ≤1.65. d. z ≥1.65 Click here to see answer by stanbon(57984)

 Question 522259: assume that adults have IQ scores that are normally distributed with a mean of 101 and standard deviation of 15. Find quartile 3 which is the IQ score seperating the top 25% from the others Click here to see answer by stanbon(57984)

 Question 522253: If a couple plans on haveing 4 children, what is the probability that there will atleast have one boy? assume boys and girls are equally likely. is that probability high enough for the couple to be very confident that they will atleast get one boy? Click here to see answer by stanbon(57984)

 Question 522249: If a card is drawn at random from a standard 52-card deck, what is the probability that the card drawn is one of the following? (a) a club (b) a black card (c) a jack Click here to see answer by stanbon(57984)

 Question 522239: If a salesman makes a sale on 70% of his sales calls. If he calls four potential clients, what is the probability he makes exactly 3 sales? What is the probability he makes exactly 4 sales? Click here to see answer by stanbon(57984)

 Question 522339: The numbers from 1 to 20 are placed in a hat. What is the probability that a random;y selected number will be greater than 8? Click here to see answer by Edwin McCravy(8999)
 Question 522339: The numbers from 1 to 20 are placed in a hat. What is the probability that a random;y selected number will be greater than 8? Click here to see answer by solver91311(17077)

 Question 522680: Here's another one I need help with: Every day Andrew wakes up and gets dressed. The probability that he will wear a long-sleeved shirt is 7/10. The probability that he will wear a long-sleeved shirt and shorts is 1/10. The probability that he will wear a long-sleeved shirt OR shorts is 9/10. What is the probability that he will wear shorts? I think it would be 9/10 less 7/10 plus 1/10 equals 3/10, but that doesn't make logical sense. I think the ANSWER should be 1/10, but if that IS right, how would I arrive at it? Click here to see answer by stanbon(57984)

 Question 522644: In a factory, historically it is known that the probability of any randomly selected lot being defective is 0.45. If out of total consignment of 200 lots, 15 lots are randomly selected, then find the probability that, 1. Exactly 7 are defective. 2. At most 6 six are defective Click here to see answer by stanbon(57984)

 Question 522679: The problem is this: A student has taken 5 tests, but lost her list of individual scores. She had added up 3 sets of total scores for 3 randomly pulled individual scores each time, and could remember those numbers. The 1st 3 randomly pulled scores equaled 190. The 2nd set of 3 randomly pulled scores equaled 230, and the 3rd set of 3 randomly pulled scores (all out of the same 5 scores) equaled 260. What were her individual scores on each of the 5 exams? This is a probability problem where the means have been given,but not the standard deviation, and it's outside of the scope of our classroom lectures and our book. Can you please help me solve this? Click here to see answer by Edwin McCravy(8999)

 Question 522775: three card are drawn fron an ordinary deck without replacement. find the probability og getting three kings Click here to see answer by stanbon(57984)

 Question 522635: Find the sample size needed to estimate the mean of a normal population with the standard deviation = 3 to within 1 unit at the 98% confidence level." Click here to see answer by stanbon(57984)

 Question 522706: Students took an Algebra 2/Trig Test with a mean of 87.5% with a standard deviation of 4.5%. What is the probability that a student scored between 84 and 100%? Click here to see answer by stanbon(57984)

 Question 522704: If you take a 30 question, multiple choice test, where each question has answer choices A, B, C, D, E, and you randomly guess all of the answers, what is the probability that you will get 20 correct? Click here to see answer by stanbon(57984)

 Question 522867: a certain class consisted of 25 males and 15 females. if 10 students were randomly selected, what is the probability that 4 males were selected? Click here to see answer by stanbon(57984)

 Question 522937: 6. Fifty faculty travel expense vouchers were submitted to the statistics department during the summer. Of these 20 contained errors. If five vouchers are selected at random what is the probability that: a. None contain errors. b. One contains an error c. Three or more contain errors d. What kind of probability distribution did you use to solve this problem? e. Make a graph of the PDF Click here to see answer by stanbon(57984)

 Question 522912: the manager of a store counted the number of sales during a 60-hour week-this is the frequency distrubution: ______________________________ number of number of sales/hr occurrences ______________________________ 6 25 number of occurrences add up to 60 7 20 so that's 60hrs/wk 8 10 9 0 I need to find the relative frequency 10 5 of 7 sales during an hour ______________________________ possible answers: 1/4, 1/3, 7/40, 7/60 Please help me with this question Click here to see answer by stanbon(57984)

 Question 522952: 15. The formula to calculate a minimum sample size is as follows: Where n is the sample size, z is the z value for the level of confidence chosen, s is the estimated standard deviation and E is the allowable error. a. Using this formula calculate the minimum sample size for a study when the level of confidence is 95 percent, the standard deviation is \$1000 and the allowable error is \$100. What actual sample size might you suggest? Explain your answer. b. How large of a sample size would be needed for a 99 percent level of confidence? What actual sample size might you suggest? Why is this sample size larger? Explain your answer Click here to see answer by stanbon(57984)

 Question 522945: 3. A sample of consumers was surveyed regarding their visits to a computer chain store and if the store was conveniently located. The following table summarizes the results of that survey: Visits Convenient Not Convenient Totals Often 60 20 80 Occasional 25 35 60 Never 5 50 55 Column Totals 90 105 195 a. What is this table called b. Are frequency of visits and convenience independent or related? Explain your answer. What is the probability of a survey respondent being convenient to a store? c. What is the probability of a survey respondent being not convenient to a store and never visiting a store in the chain? Click here to see answer by stanbon(57984)

 Question 522944: Can someone please help me with this problem. Please, please. When playing bingo, 75 balls are placed in a bin and balls are selected at random. Each ball is marked with a letter and number as indicated in the following chart. B I N G O 1-15 16-30 31-45 46-60 61-75 For example, there are balls marked B1, B2 up to B15; I16, I17, up to I30; and so on. Assuming one bingo ball is selected at random, determine the odds in favor of it being B9 Click here to see answer by sudhanshu_kmr(1152)

 Question 523005: Hi, I am having problems with a chi-square related question. Here is the question: (a) Write the null and alternative hypothesis for a one-sided test to determine whether men are, on average, heavier than men from 20 years ago. These are the hypotheses I have come up with: Null Hypothesis – There is no difference between the average weight of men now and 20 years ago. Alternative Hypothesis – Men, on average, are heavier than men from 20 years ago. (b) Carry out a test of the hypothesis in (a) at the 5% significance level, i.e. calculate the: - Test statistic - Critical value of the Normal Distribution for a one-sided test at the 5% significance level This is where I am having problems. I know how to do chi-square (I'm assuming we have to use chi-square as that's what we have been using in the other questions) when I have the data, ie. observed and expected. What I am unsure about is what data to use as this is all I have been provided with: From data collected 20 years ago, the average weight of an adult male was 71 kilograms and the standard deviation 7.2 kilograms. Table: Weights (in kilograms) of a new random sample of 29 adult males 59 79 61 81 62 82 66 68 83 69 84 70 73 77 84 74 88 76 78 91 78 74 86 59 66 73 74 75 76 So far I have been using the averaging weight of the new sample of men which is 74.7 and the average weight from 20 years ago which is 71 and trying to use a one-way chi-square method. So basically my table looks like this: Today 20 Years Ago Weight 74.7 71 First of all is this the correct way of doing it? If so, my next dilemma is trying to figure out the expected frequency from the observed. I know how to calculate the expected from a contingency table of 2 or more rows, but when i try to apply the same formula to just one row, the expected ends up the same as the observed, which surely cant be right? If I am going about it totally the wrong way, any advice would be appreciated. I am not a mathematician or even studying it ,so apologies for my lack of knowledge. Hopefully someone can help me out. Ryan Click here to see answer by stanbon(57984)

 Question 523155: Of 150 adults who tried a new rum-flavored peppermint patty, 87 rated it excellent. Of 200 children sampled, 123 rated it excellent. Using the .10 level of significance, can we conclude that there is a significant difference in the proportion of adults and the proportion of children who rate the new fla¬vor excellent? (a) State the null hypothesis and the alternate hypothesis. (b) What is the probability of a Type I error? (c) Is this a one-tailed or a two-tailed test? (d) What is the decision rule? (e) What is the value of the test statistic? (f) What is your decision regarding the null hypothesis? (g) What is the p-value? Explain what it means in terms of this problem. Click here to see answer by stanbon(57984)

 Question 523192: 8. Playtime Toys has fifty employees of whom forty are members of the union. Five employees are selected at random to form a committee to meet with management to negotiate shift starting times. a. What kind of probability distribution will you use to solve this problem? b. What is the probability that four of the committee members will be union members? c. What is the probability that four of the committee members with non union members? Click here to see answer by stanbon(57984)

 Question 523178: Given 8 students, 4 of which are females, if 2 students are selected at random, without replacement, what is the probability that both students are female? Click here to see answer by stanbon(57984)

 Question 523261: Let Z be a standard normal random variable. Use the calculator provided to determine the value of C such that P(Z less then or equal to C)= .2743 Click here to see answer by stanbon(57984)

 Question 523276: From a standard 52-card deck, what are the odds of drawing a 10, a face card, an ace, or a spade? Click here to see answer by stanbon(57984)

 Question 523260: Let be a standard normal random variable. Use the calculator provided to determine the value of such that P(0.64 less then or equal to Z less then or equal to C)= .2389 Click here to see answer by stanbon(57984)

 Question 523258: pleaseee i really need your help for solving these two equatiooooon:(:( anad thank u very muchhhh first q;the average score on a special test of knowledge of wood refinishing has a mean of 53 and a standard deviation of 6 .using chebyshe've theorem.find the range of values in which at least 75% of the scores will lie... second q:the average of the number of trials it took a sample of mice to learn to traverse a maze was 12.the standard deviation was3.using chebyshev's theorem,find the minmum percentage of data values that will fall in range 4 to 20 trials Click here to see answer by stanbon(57984)

 Question 523347: A basketball team's star 3-point shooter takes six 3- point shots in a game. Historically, he makes 40% of all 3-point shots taken in a game. State at the outset what assumptions you have made. (a) Find the probability that at least two shots were made. (b) Find the probability that exactly three shots were made. (c) Find the mean and standard deviation of the num¬ber of shots made. (d) Find the mean and standard deviation of the total number of points scored as a result of these shots. Click here to see answer by stanbon(57984)

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