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

Tutors Answer Your Questions about Probability-and-statistics (FREE)

Question 439886: A light bulb has an average life of 500 hours with a std. deviation of 100 hours. This can be approx. by a normal distr. curve. An amusement park buys and installs 10,000 of such bulbs. Find the total number than can be expected to last for:

a) Less than 500 hours
b)more than 440 hours
Click here to see answer by ewatrrr(10682)

Question 440225: Linda has a bird feeder in her backyard. She noticed that a certain cardinal visits the bird feeder every 10 hours and that a certain woodpecker visits the bird feeder every 7 hours. She last saw the two birds visiting the bird feeder together on Monday at 10:00 a.m.
At what time and what day will the two birds visit the bird feeder together?

Click here to see answer by rwm(914)

Question 440237: in a survey 39% of people say they think tattoos are beautiful. you chose 21 random people and ask them, what is the probability that at least 16 people think they are? At most 4?
Click here to see answer by rwm(914)

Question 440273: There are 27 students in a class, 14 are girls. If 5 students got an A on a test, what is the probability that it was 3 boys and 2 girls?

Click here to see answer by stanbon(57285)

Question 440295: Consider the expierement of drawing two cards without replacement from an ordinary deck of 52 playing cards. What are the odds in favor of drawing a spade and a heart?
I am really not sure where to start here. This is what I started to do but don't believe it is right.
P(spade)=13/52 P(heart without replacement)=13/51 but I have no idea if that is right or where to go from there.
Click here to see answer by jorel1380(2518)

Question 440313: FIND THE PROBABILITY OF CORRECTLY ANSWERING THE FIRST 4 QUESTIONS ON A MULTIPLE CHOICE TEST IF RANDOM GUESSES ARE MADE AND EACH QUESTION HAS 3 POSSIBLE ANSWERS.
Click here to see answer by jorel1380(2518)

Question 354383: A coin-operated coffee machine made by BIG Corporation was designed to discharge a mean of 7.3 ounces ounces of coffee per cup. If it dispenses more that that on average, the corporation may lose money, and if it dispenses less, the customers may complain.
Believing that the mean amount of coffee dispensed by the machine, is less than 7.3 ounces, BIG plans to do a statistical test of the claim that the machine is working as designed. Technicians gather a random sample of fill amounts and find that the mean of the sample is 7 ounces and that the standard deviation is ounces.
Based on this information, answer the questions below.
What are the null hypothesis (H0) and the alternative hypothesis (h1) that should be used for the test?
In the context of this test, what is the type II error? A type II error is (rejecting or failing to reject), the hypothesis that the mean is (less than, less than or equal to, greater than, greater than or equal to, not equal to, equal to) 7, 7.3 or 0.3
Suppose that BIG decides not to reject the null hypothesis. What sort of error might it be making? Type I or Type II

Click here to see answer by lobos49mom(1)

Question 440360: The probability of selecting a rotten apple from a basket is 12%. What is the probability of selecting three good apples when selecting one from each of three different baskets?
Click here to see answer by jorel1380(2518)

Question 440373: Find the coefficient of in the expansion of ^10
Click here to see answer by stanbon(57285)

Question 440446: If I have a 5 yr. old boy who has a BMI of 18 and the BMI is considered a normally distributed variable, whose mean for this age boy is 15.41914 and whose standard deviation is 0.075992. How can I calculate the PERCENTILE ranking for this boy. Please show me HOW you achieve the numbers--I need to see HOW to calculate the result--PLEASE DO NOT USE A TABLE. I want to write an excel program for our school nurse and I need the EQUATION to plug in and test for in excel. Thank you.
Click here to see answer by stanbon(57285)

Question 440437: suppose you select an integer from 100 to 200 at random what is the probability?
Click here to see answer by richard1234(5390)

Question 440216: Can the word "LINERS" be played from the letters I, E, N, L, S, T, R as the first move in a Scrabble game?
Click here to see answer by richard1234(5390)

Question 440489: The theoretical probability of undesirable side effects resulting from taking Grebex is 1 in 20. If 100 people take Grebex to lower their blood pressure, how many will encounter undesirable side effects?
Click here to see answer by edjones(7569)

Question 440511: a bag contains 10 marbles (4 red, 2 white and 4 blue). if you select 3 marbles at random from the bag without replacement, what is the probability ( as a common fraction) that exactly two of the marbles selected will be red?
Plz help me fast this problem is killing me!
Click here to see answer by edjones(7569)

Question 440530: One thousand raffle tickets are sold for $5.00 each. One grand prize of $1000 and two consolation prizes of $100 each will be awarded. Jeremy purchases one ticket. Find his expected value.
Click here to see answer by edjones(7569)

Question 440592: Consider the experiment of drawing two cards without replacement from an ordinary deck of 52 playing cards....what are the ODDS in favor of drawing a spade and a heart?
This is what I have: P(Spade)=13/52, P(heart without replacement)=13/51 so then I multiply and get 169/2652 reduced to 13/204. Now that is the probability of getting a heart and a spade, how to I find the odds? The formula for finding odds in favor is P(A)/1-P(A), so would my problem be set up as
(13/204) / 1-(13/204)? If thats how it is set up, how do I carry out the math? I am very confused, please help! The answer in the book is 13:91 but I can not figure out how they got there.

Click here to see answer by richard1234(5390)

Question 440553: What is the formula to find the following; The probability that the mean of a sample of 50 babies' weights lies between 3330 and 3510, with a standard deviation of 493.5 (answer given is .803, how do I get that????) Thanks!

Click here to see answer by Edwin McCravy(8893)

Question 440589: Let "x bar" be the sample mean for a random sample of 12 observations from a uniform (0,1). What is the mean and variance of "x bar"?
Click here to see answer by robertb(4012)

Question 440686: if I select the correct answer 18% of the time what would be my longest run of incorrect answers
Click here to see answer by robertb(4012)

Question 440709: What is the probability of rolling a prime number on a six sided number cube.
Click here to see answer by ewatrrr(10682)

Question 440691: from a pack of 52 playing cards, three cards are drawn at random.Find the probability of drawing a king , a queen and jack.
Click here to see answer by ewatrrr(10682)

Question 440598: seven out of every 20 homes that own at least one television have two televisions. what percent of the homes that own at least one television have two televisions?
Click here to see answer by ewatrrr(10682)

Question 440570: four items are to be randomly selected from the first 25 items on an assembly line in order to determine the defect rate. How many different samples of 4 items can be chosen?
Click here to see answer by ewatrrr(10682)

Question 440574: In a certain college, 33% of the physics majors belong to ethnic minorities. Find the probability that 7 or more belong to an ethnic minority from a random sample of 10 students who are physics majors.
Click here to see answer by ewatrrr(10682)

Question 440361: Tim has 4 table tennis balls with small cracks. His friend accidentally mixed them in with 16 good balls. If Tim randomly picks 3 table tennis balls, what is the probability that at least 1 is cracked?
Click here to see answer by ewatrrr(10682)

Question 440736: A jar contains 12 M&M candies, of the 12: 2 are red, 3 are green, 3 are blue, 4 are purple
What is the probability that you will get 2 blue and 1 green?
Click here to see answer by ewatrrr(10682)

Question 440784: problem 1) Ninety students will graduate from Lima Shawnee High School this spring. Of the 90 students, 50 are planning to ttend college. Two students are to be picked at random to carry flags at graduation.
A) What is the probability both of the selected students plan to attend college?
B) What is the probability one of the two selected students plans to attend college?
I know that these are counting problems that involve the basic counting rule, permutations and combinations. I need the formulas and answers. I am extremly lost.
problem 2) a survey of undergraduate students in the Shool of Business at Northern University revealed the following regarding the gender and majors of the students.
Gender Accounting Management Finance total
Male 100 150 50 300
Female 100 50 50 200
total 200 200 100 500
A) What is the probibility of selecting a female student?
B) What is the probability of selecting a 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 account 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 selected are accounting majors?
Problem 3) Reynolds Construction Company has agreed not to erect all "look-alike" homes in a new subdivision. Five exterior designs are offered to potential home buyers. The bulider has standardized three interior plans that can be incorporated in any of the five exteriors. How many different ways can the exterior and interior plans be offered to potewntial home buyers?
Problem 4) A puzzle in the newspaper presents a matching problem. The names of 10 in one U.S. presdents are listed in column, and their vice presidents are listed in random order in the second column. The puzzle asks the reader to match each president with his vice president. If you make the matches randomly, how many matches are possible? What is the probability all 10 of your matches are correct?
Thank you in advance for this much needed help.
Click here to see answer by stanbon(57285)

Question 440720: Use the given level of confidence and sample data to construct a confidence interval for the population proportion p.
Given: 92% confidence level; n=107; x=66
Click here to see answer by stanbon(57285)

Question 440809: I need someone to show me how to do these homework questions please.
5. Suppose an A is worth 4 points, a B 3 points, a C 2 points, a D 1 point, and an F 0 points. If I earned A’s in 60%, B’s in 25%, C’s in 10%, and D’s in 5% of the college credits I have completed, what’s my GPA (one digit after decimal point)?
Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen.
7. Find the probability that it will last less than 10 years (4 digits after decimal point).
8. Find the probability that it will last more than 16 years (4 digits after decimal point).

Click here to see answer by edjones(7569)

Question 440766: Three cards are drawn from a deck of cards with replacement. Determine the probability of drawing 3 kings
Click here to see answer by jorel1380(2518)

Question 440816: How many license plates can be made using two letters and three digits? (Repetition of letters and digits is allowed)
Click here to see answer by jorel1380(2518)

Question 440888: a photographer is taking pictures of a bride and groom and their 6 attendants. if she takes photographs of 3 people in a group, how many different groups can she photograph
Click here to see answer by jorel1380(2518)

Question 440866: The time spent waiting in the line is approximately normally distributed. The mean waiting time is 7 minutes and the standard deviation of the waiting time is 2 minutes. Find the probability that a person will wait for less than 11 minutes. (Round your answer to 4 decimal places)
Click here to see answer by stanbon(57285)

Question 440625: suppose you are dealt a hand of three cards at random from a deck of 32 cards consisting of 4 aces, 4 2s, 4 3s and so on up to 4 8s. what is the probability that your hand will have atleast 2 4s? what is the probability that none of your cards will have the same numeric value?
i tried (4/32)(3/31) for the first one and it was wrong
i tried (1/32)(1/31)(1/30) for the second but that didn't work either
Click here to see answer by scott8148(6628)

Question 440968: A random spinner has equal-sized regions numbered 1 through 18. The spinner stops on an even number or a multiple of 3.
Click here to see answer by Alan3354(30993)

Question 441122: A coin was tossed five times. whats the probability that it will show heads or tails atleast once.
Click here to see answer by stanbon(57285)

Question 5081: Help--how do i figure this one out? Driving me crazy !!!
Twenty bearded men gather. Ten have eight-inch beards, six have ten-inch beards, and four have twelve-inch beards. What is the expected length of a randomly selected man from this group?
Tried 10/20 x 6/20 x 4/20 =12inches, that doesn't seem right. Please help!
Click here to see answer by JWG(21)

Question 441203: 3.18 Suppose A and B are events with 0 < P(A) < 1 and 0 < P(B) < 1.
a. If A and B are disjoint, can they be independent?
b. If A and B are independent, can they be disjoint?
c. If A ⊂ B, can A and B be independent?
d. If A and B are independent, can A and A ∪ B be independent
Click here to see answer by robertb(4012)

Question 441206: kamal and monica appeared for an interview for two vacancies. the probability of kamal's selevtion is 1/3 and that of monica's selection is 1/5. find the probability that only one of them will bw selected.
Click here to see answer by Euler(11)

Question 441142: The standard deviation of test scores on a certain achievement test is 11.4. A random sample of 80 scores on this test had a mean of 73.6 . Based on this sample, find a 90% confidence interval for the true mean of all scores. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.

What is the lower limit of the 90% confidence interval
What is the upper limit of the 90% confidence interval
Click here to see answer by stanbon(57285)

Question 441217: three card are drawn is succession without replacement from an ordinary deck of playing cards.find the probability that the first card is red ace,the second card is ten or jack,and the third card is greater than 3 but less than 7.
Click here to see answer by stanbon(57285)

Question 441166: to test the hypothesis that students who finish an exam first get better grades, professor hardtrach kept tract of the order inwhich papers were handed in, the first 25 papers showed a means of 77.5 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 significant defference at a=.0? perform a one-tail test
Click here to see answer by stanbon(57285)

Question 441087: The question reads: A university has 10,000 students of which 4,000 are male and 6,000 are female. If a class of 30 students is chosen at random from the university population, find the mean and standard deviation of the number of male students.
After using the formula for binomial distribution mean (np) and standard deviation (square root of np(1-p), I came up with the answer...
mean= 12
standard deviation = 2.68
I am confused when to use which equation so I was hoping you could verify my answer. Thank you!
Click here to see answer by stanbon(57285)

Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585, 586..630, 631..675, 676..720, 721..765, 766..810, 811..855, 856..900, 901..945, 946..990, 991..1035, 1036..1080, 1081..1125, 1126..1170, 1171..1215, 1216..1260, 1261..1305, 1306..1350, 1351..1395, 1396..1440, 1441..1485, 1486..1530, 1531..1575, 1576..1620, 1621..1665, 1666..1710, 1711..1755, 1756..1800, 1801..1845, 1846..1890, 1891..1935, 1936..1980, 1981..2025, 2026..2070, 2071..2115, 2116..2160, 2161..2205, 2206..2250, 2251..2295, 2296..2340, 2341..2385, 2386..2430, 2431..2475, 2476..2520, 2521..2565, 2566..2610, 2611..2655, 2656..2700, 2701..2745, 2746..2790, 2791..2835, 2836..2880, 2881..2925, 2926..2970, 2971..3015, 3016..3060, 3061..3105, 3106..3150, 3151..3195, 3196..3240, 3241..3285, 3286..3330, 3331..3375, 3376..3420, 3421..3465, 3466..3510, 3511..3555, 3556..3600, 3601..3645, 3646..3690, 3691..3735, 3736..3780, 3781..3825, 3826..3870, 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