Answers created by Will

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• How can i calculate the probability of waiting for a certain bus to come? Difficult but interesting
  
• Question #33988
  
• If #5^-x = 1/3#, then what is the value of #25^x#?
  
• A research firm wants to estimate the true population proportion of families having annual incomes that exceed $100,000 in a particular city. If it costs $20 to obtain each sample value, how large must the sampling budget be?"
  
• What measure of central tendency is not influenced by outliers?
  
• Question #0325b
  
• "Compute the probability of #x# successes in the #n# independent trials of the experiment" ?
  
• Question #773b6
  
• If C is the union of A and B, how do you calculate the standard deviation of population C if you know the standard deviations of A and B? What if A and B are of different sizes?
  
• Why can't a confidence level be 100%?
  
• How do you calculate a 95% confidence interval without the mean?
  
• If two events are complementary, are they mutually exclusive too?
  
• Question #1efa6
  
• A coal company wants to determine a 95% confidence interval estimate for the daily tonnage of coal that they mine. Assuming that the standard deviation of daily output is 200 tons, how many days should they sample so that the margin of error is 39.2 tons?
  
• Let #X# be a binomial random variable with #p=0.3# and #n=15#. What is #P(X>9)#?
  
• A class contains 5 boys and 6 girls. The teacher is told that 3 of the students can go on a school trip, and selects them at random. What is the probability that 2 boys and 1 girls are selected?
  
• Three fair coins are tossed. If all three coins show heads, then the player wins $15. If all three coins show tails, then the player wins $10. If it costs $5 to play the game, what is the player's expected net gain or loss at the end of two games?
  
• Question #fa68c
  
• Question #bb618
  
• How is a binomial distribution different from a Bernoulli distribution?
  
• A space shuttle requires 3-out-of-4 of its main engines to achieve orbit. Each engine has a reliability of 0.97. What is the probability of achieving orbit?
  
• A hole has to be 2 ft deep. William is able to dig at a rate of #1/2# ft. per minute. How do you write an equation for when #y#, the amount he has left to dig is a function of #x#, the amount of time he has been digging?
  
• Two power generating units A and B operate in parallel to supply the power requirement of a small city. If there is failure in the power generation what is the probability that the city will have its supply of full power?
  
• The Cyclone Coaster has 16 cars. Some of them hold 2 passengers and some hold 3 passengers. If there is room for 36 people altogether, how many cars hold 3 passengers?
  
• Question #0c12f
  
• Question #a71e9
  
• How do you implicitly differentiate #-y=y-sqrt(x^3y-y) #?
  
• Question #eca69
  
• What is #f(x) = int x-3e^x dx# if #f(1) = 0 #?
  
• How do you find the zeros of the polynomial function with equation # f(x) = 2(x-5)(x+4)^2#?
  
• The incubation time for Rhode Island Red chicks is normally distributed 27 days and standard deviation of approximately 3 days. If 1000 eggs are incubated, how many chicks do we expect will hatch in 27 to 33 days?
  
• Out of 7 lottery tickets 3 are prize-winning tickets. If someone buys 4 tickets what is the probability of not winning any prize at all?
  
• The value of a new car bought for $20,000 decreased by 10% per year. How do you write an exponential decay model for the value of the car and use the model to estimate the value after one year?
  
• How do you expand #(2y^3+x)^5#?
  
• How do you solve the quadratic #9a^2+3=-27# using any method?
  
• How do you calculate the standard deviation of a bounded probability distribution function?
  
• Suppose you are playing a game in which two fair dice are to rolled. To make the first move, you need to roll doubles or a sum of 3 or 11. What is the probability that you will be able make the first move?
  
• How do you implicitly differentiate #-1=1/(xy)-1-3y^2#?
  
• If you tossed a coin 10 times, what is the probability of landing on tails every time?
  
• Is expected value affected by changes in variance?
  
• What are the mean and standard deviation of the probability density function given by #p(x)=k/x # for # x in [3,8]#, with k being a constant such that the cumulative density is equal to 1?
  
• Can you determine a OLS regression line from just two data points?
  
• How do you find the definite integral of # (xdx) / ((x^2 + 1)ln(x^2 + 1))# from #[1,2]#?
  
• Carl has a piece of toast that has jelly on one side, and he dropped it twice. Both times, it landed with the jelly side up. If he drops it two more times, what is the probability that it will have landed jelly side up a total of three times?
  
• How do you prove #sin(alpha+beta)sin(alpha-beta)=sin^2alpha-sin^2beta#?
  
• The average time a subscriber spends reading the local newspaper is 49 minutes. For the 10% who spend the most time reading the paper, how much time do they spend?
  
• When a data set is normally distributed, about how much of the data fall within two standard deviations of the mean?
  
• How do you solve #2x^2-6=42#?
  
• How do you solve using completing the square method #x^2+4x-3=0#?
  
• How do you simplify #(y^6/y) ^-2# using only positive exponents?
  
• Of the 232 airports available for public use in Themeliville, 121 are paved and lighted. For a simple random sample of 50, what is the probability that between 27 and 31 of the airports in the sample will be paved and lighted?
  
• How do you find the derivative of # (2x-1)^3#?
  
• How do you implicitly differentiate #-y= 4x^3y^2+2x^2y^3 #?
  
• Question #eadbc
  
• How do you solve #(2k-1)^2=9#?
  
• How do you solve #ln(-5n)=ln(4-3n)#?
  
• What is the implicit derivative of #xy+ysqrt(xy-x) =8 #?
  
• How do you solve #8x^2 - 5x - 3 = 0# by completing the square?
  
• How do you integrate #int-12x^2(-4x^3+2)^-3# using substitution?
  
• How do you integrate #e^7x^3 x^2 dx#?
  
• Could someone explain to me the Rule of Compound Probability involving "and"?
  
• The mean weight of 32 math students is 98.3 lb. If the students could all stand on the scale together, what would their total weight be?
  
• In a statistics class there are 11 juniors and 6 seniors; 4 of the seniors are females, 6 of the juniors are males. If a student is selected at random, what is the probability that the student is either a senior or a male?
  
• Is the following an arithmetic sequence? 5, 0, -5, -10,.?
  
• Question #7d4be
  
• How do you differentiate #g(x) = (1/x^3)*sqrt(x-xe^(x))# using the product rule?
  
• How do you write an exponential function to model the situation, then find the value of the function after 5 years to the nearest whole number. A population of 200 people that decreases at an annual rate of 6%?
  
• What is the mathematical formula for the pooled variance of two populations?
  
• How do you solve #ln(n^2+12)=ln(-9n-2)#?
  
• How do you apply Bayes' theorem to continuous random variables?
  
• The probability that a train leaves on time is 0.9. The probability that the train arrives on time and leaves on time is 0.36. What is the probability that the train arrives on time, given that it leaves on time?
  
• How do you find the number of terms n given the sum #s_n=2178# of the series #2+16+30+44+58+...#?
  
• A yogurt shop sells #7# flavors of frozen yogurt and #11# different toppings. How many choices are possible for a single serving of frozen yogurt with one topping?
  
• What is the lower bound of a random variable's variance?
  
• You deposit $700 in an account that pays 12% annual interest compounded annually. How do you write a recursive function to model the situation?
  
• What is the standard deviation of is #sigma(X)=2sigma(Y)#, what is #sigma(X+Y)#?
  
• Suppose an experiment consists of rolling a fair, six-sided number If the cube. experiment were repeated 300 times, how many times would you predict the number cube would land on a value greater than 4?
  
• A certain bacterial culture doubles in number every hour. If 1 bacterium is placed in a glass beaker at 8 A.M., how many will be there at 12 midnight?
  
• How do you solve #-6log_3(x-3)=-24#?
  
• Question #c3149
  
• How do you simplify #[x^-1+y^-1]/[x^-2-y^-2]#?
  
• Out of 8 men and 10 women, a committee consisting of 6 men and 5 women is to be formed. How many such committees can be formed when one particular man A refuses to be a member of the committee in which his boss's wife is there?
  
• Question #c7427
  
• How do you find the exponential model #y=ae^(bx)# that goes through the points (0,4) and (5, 1/2)?
  
• How do you solve #8^(5x)=16^(3x+4)#?
  
• Question #c4443
  
• What is the expected value of a lottery offering $100 or a consolation prize of $2 if you do not win, when the probability of winning is .4?
  
• Question #5a6e7
  
• If you are comparing subgroups of a data set, how can you determine if the variance between subgroups is significant?
  
• The freshman class has 160 students. Each freshman must write three reports from a list of 12 novels that the teacher has assigned them to read. How many different combinations of novels can a freshman student choose to write reports on?
  
• If random variable X has a probability density function of f(x)=1/x on the interval[e,e^2], what is the standard deviation of X?
  
• Question #59f14
  
• What is the probability that out of 245 booked reservations that exactly 224 people show up for the flight? What is the probability that no more than 224 people show up? How are these two probabilities different?
  
• What is the log-likelihood function?
  
• How do you solve #log(x+3)log(x-3)=1#?
  
• What is the range of a logistic function?
  
• In how many ways can 6 graduates line up to receive their diplomas, if there are 4 girls and 2 boys and the girls will receive their diplomas first?
  
• If $12000 is invested at 4% compound quarterly, what is the amount after 8 years?
  
• How do you solve #Ln(e^(x) - 2)=3#?
  
• How do you solve #x^2 = 5x +2#?
  
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