# Recently Submitted Homework Problems: statistics

155. A lawyer commutes daily from his suburban home to his midtown office. the average time for a one-way trip is 24 minutes, with a standard deviation of 3.8 minutes. Assume the distribution of trips times to be normally distributed. Find the probability that 2 of the next 3 trips will take at least half(1/2) hour. (Answered)463. The ritz carlton hotel used a customer opinion questionare to obtain performing data about its dining and entertainment services. Customers were asked to rate six factors: Welcome, Service, food, menu, appeal, atmosphere and overall experience. Data were recorede for each factor 1 for fair 2 for average and 3 for good and 4 for excellent

a) The customers response provided data for six variables. Are the variables quantative or qualitative?

b) What measurement of scale if used?

(Answered)

5237. xbar=375, s=130, n=20 the mean distance is a least 425 meters. Use the hypothesis procedure to determine if there were sufficient evidence at a level of significance of 0.025 to refute this claim.(Answered)

852. let the random variable X represent the weight of male black bears before they begin hibernation. research has shown that X is approximately normally distributed with a mean of 250 pounds and a standard deviation of 50 pounds. what is P(X>325 pounds)?(Answered)

852. let the random variable X represent the weight of male black bears before they begin hibernation. research has shown that X is approximately normally distributed with a mean of 250 pounds and a standard deviation of 50 pounds. what is P(X>325 pounds)?(Answered)

920. The number of years of education of self-employed individuals in the U.S. has a population mean of 13.6 years and a population standard deviation of 3.0 years. If we survey a random sample of 100 self-employed people to determine the average number of years of education for the sample, what is the mean and standard deviation of the sampling distribution of x-bar (the sample mean)? Enter your answers below to one decimal place, e.g. 0.1.(Answered)

1019. There are five envelopes in one box. One envelope contains a penny, one envelope contains a nickel, one a dime, one a quarter, and one a half dollar. A person selects an envelope. Find the expected value of the draw.(Answered)

1019. There are five envelopes in one box. One envelope contains a penny, one envelope contains a nickel, one a dime, one a quarter, and one a half dollar. A person selects an envelope. Find the expected value of the draw.(Answered)

1321. Statistics Question: A new contraceptive pill is shown to be 75% effective in preventing pregnancy. In an experiment this contraceptive pill is administered in an independent sample of 15 women. What will the probability that the pill will be effective in all 10 women?(Answered)

1305. the phillies were accused of cheating their beer customers by not putting enough beer in their 12oz cups. when 15 cups were sselected at random, they were found to have a mean of 11.7 ounces with a standard deviation of 0.5 ounces. At the .01 signifance leel, est the claim that the customers are being cheated(Answered)

1470. The following data give the weekly expenditures (in dollars) on fruit and vegetables for 30 households randomly selected from the households who incurred such expenses.

4.57, 3.95, 6.95, 3.80, 1.50, 2.99, 7.84, 5.05, 8.00, 14.75, 9.33, 1.05, 5.08, 7.00, 9.60, 18.99, 9.15, 11.32, 4.75, 9.95, 3.63, 1.99, 1.39, 13.09, 19.31, 11.15, 7.73, 12.00, 7.58, 16.53

a. Construct a frequency distribution table using the less than method to write classes. Take $0 as the lower boundary of the first class and $4 as thw width of each class.

b. Calculate the relative frequencies and percentages for all classes.

c. Construct a histogram for the frequency distribution.(Answered)

1647. 10,000 New York City Road Runner members were surveyed and classified based on the number of hours per week that they ran. The runners were classified as 'Running more than 10 hours per week' and 'Running less than 10 hours per week.' Runners were then followed for the next 5 years to determine which runners develop stress fractures.

Incidence rates of stress fractures per year per 1,000 runners:

Running less than 10 hours per week: 0.28

Running more than 10 hours per week: 0.63

Calculate the relative risk of developing stress fractures associated with running more than 10 hours per week.

Describe in words how you would interpret the results.

Calculate the attributable risk of stress fractures associated with running more than 10 hours per week.

Describe in words how you would interpret the results.

(Answered)

2119. Organize the data into a class interval frequency distribution using 10 intervals with frequency (f) and relative frequency (rf).

Data Set: 100, 97, 99, 70, 72, 75, 82, 68, 85, 88, 71, 77, 93, 94, 54, 59, 83, 87, 98, 84, 72, 96, 98, 89, 74, 98, 77, 82, 83, 98, 90, 95, 85, 76, 62, 72, 36, 21, 42, 91, 90, 81, 78, 79, 74, 82, 98(Answered)

2489. Need help performing a statistical hypothesis test(Answered)

2489. Need help performing a statistical hypothesis test(Answered)

2725. According to the Current Population Survey of the Census Bureau, 67% of children live with both parents, 23% live with their mother only, and 5% live with their father only. The rest live with neither parent. If we choose a child at random, what is the probability that the child lives with only ONE parent (father OR mother)? (Answered)

2907. For a sample of measurements x-bar = 10m, median = 13m standard deviation = 4m and sample variance = 16m^2

a) if the data is changed to centimeters (i.e. yi=100xi) then find the new set of measurements

Here, I just multiplied all of the above answers by 100, and assumed that that was correct BUT, if I use that logic for part b, it starts to get confusing...

b) IF the data is transformed to yi=(xi-10)/4 find the new measurements

... if I try to do the same thing (sub the x measurements into the new formula) I end up with an average length of 0, which makes no sense to me, and makes me think that I must be doing something wrong!

(Answered)

3195. In the November 1990 issue of Chemical Engineering Progress, a study discussed the percent purity of oxygen from a certain supplier. Assume that the mean was 99.61 with a standard deviation of 0.08. Assume that the distribution of percent purity was approximately normal.

a) What percentage of the purity values would you expect to be between 99.5 and 99.7?

b) What purity value would you expect to exceed exactly 5 % of the population?(Answered)

3346. From the data given below calculate the value of first and third quartiles, second and ninth deciles and forty-fifth and fifty-seventh percentiles.

Height in

centimeters Number of students Cumulative

frequency

161-167 79 79

167-173 92 171

173-179 60 231

179-185 22 253

185-191 5 258

191-197 2 260

Total 260

(Answered)

3346. From the data given below calculate the value of first and third quartiles, second and ninth deciles and forty-fifth and fifty-seventh percentiles.

Height in

centimeters Number of students Cumulative

frequency

161-167 79 79

167-173 92 171

173-179 60 231

179-185 22 253

185-191 5 258

191-197 2 260

Total 260

(Answered)

3406. 1) Dina is producing umbrellas. The average variable cost for umbrella is constant at $5.00 per unit. The firm is selling 1000 units a week. Fixed cost of producing umbrellas is $5000. The market price for the product is $12.00 per unit.

a. Calculate total profit.

b. Calculate the break-even level of output.

c. If the firm sets a target of $3400 as their weekly profit, how many units of output should it sell?

a. ($12,000-$5,000)/$12,000 = 0.5833 or 58.33%

b. $5000 + 5Q = 12Q

i. $5000 = 12Q – 5Q

ii. $5000 = 7Q

iii. $5000/7

iv. = 714.30 units

c. $3400/12Q

(Answered)

3905. HELP ME SOLVE THIS PROBLEM-FIND THE MEAN DEVIATION OF THESE NUMBERS 3,3,4,5,5,6,7,8,9,10(Answered)

3905. HELP ME SOLVE THIS PROBLEM-FIND THE MEAN DEVIATION OF THESE NUMBERS 3,3,4,5,5,6,7,8,9,10(Answered)

3998. Suppose the scores of certain standardized test are normally distributed with mean 500 and standard deviation 80. What percent of the test takers have a score of 440 or less?(Answered)

4030. In an area; the proportion of younger people 0.2, older people 0.3 and other 0.5. equates to odds of 1 in 5, 1 in 3.3 and 1 in 2 respectively. I want to know the linear distance to travel as a younger person to find an older person and vice versa. Thanks (Answered)

4485. Suppose we want to study the errors found in the performance of a simple task. We ask a large number of judges to report the number of people seen entering a major department store in one morning. Some judges will miss some people, and some will count others twice, so we don't expect everyone to agree. Suppose we find that the mean number of shoppers reported is 975 with a standard deviation of 15. Assume that the distribution of counts is normal.

a. What two values of X (the counts) would encompass the middle 50% of the results?

b. 75% of the counts would be less than ______.

c. 95% of the counts would be between ______ and ______.

(Answered)

5211. Carlos,Minerva, Rafael, Yolanda are students in a class of 14.4 students in this class are to be selected in random to present a report. What is the probability they are selected in that order. Round to decimal six places(Answered)

5268. a shipment of 250 netbooks contains 3 defective units. determine how many ways a vending maching company can buy three of these units and receive a) no defective units b) all defective units c) at least one good unit

(Answered)

5413. Let X and Y be independent Poisson random variables with parameters lambda and mu. By computing its PMF, show that X + Y is itself a Poisson random variable with parameter lambda + mu.(Answered)