Homework+7

2) You work for the FTC. A manufacturer of detergent claims that the mean weight of detergent is at least 6.5 lb. You take a random sample of 64 containers. You calculate the sample average to be 6.43 lb. with a standard deviation of .14 lb. At the 0.02 level of significance, is the manufacturer correct?

A large milling machine produces steel rods to certain specifications. The machine is considered to be running normally if the standard deviation of the diameter of the rods is at most 0.42 millimeters. The line supervisor needs to test the machine is for normal functionality. The quality inspector takes a sample of 45 rods and finds that the sample standard deviation is 0.49. What is the test statistic? Select one: а. 59.89 b. 48.63 с. 50.50 d. 52.45

A simple random sample of 8 employees of a corporation provided the following information. Employee Age Gender 1 2 3 21 37 26 W M W 4 5 6 7 8 44 48 50 25 22 W W M M M (a) Determine the point estimate for the average age of all employees. (b) What is the point estimate for the standard deviation of the population? (Round your answer to four decimal places.) (c) Determine a point estimate for the proportion of all employees who are female.

10. 7 students were asked how many pencils they had. The responses were 2, 5, 8, 3, 1, 6, and 4. a. Calculate the sample mean 8. Find the sample standard deviation C Find the Q1, Q3, and the interquartile range.

In one of its Spring catalogs, L.L. Bean advertised footwear on 29 of its 192 catalog pages. Suppose we randomly surgery 20 pages. We are interested in the number of pages that advertise footwear. Each page may be picked at most once. Calculate the standard deviation

SCCoast, an Internet provider in the Southeast, developed the following frequency distribution on the age of Internet users. Find the mean and the standard deviation. (Round squared deviations to nearest whole number and final answer to 2 decimal places.)   Age (years) Frequency 10 up to 20   3   20 up to 30   7   30 up to 40   18   40 up to 50   20   50 up to 60   12

Question of the day. The mean weekly sales of the chocolate bar in candy stores was 146-3 bars per store. After an advertising campaign the mean weekly sales in 22 stores for a typical week increased to 153-7 and showed a standard deviation of 17-2. Was the advertising campaign successful?

QUESTION 28 "For a population with a mean = 440 and a standard deviation = 110, what is the X value corresponding to z = 2.67? (Be sure to round answer to the second decimal place)."

d) Suppose this is a representative sample of births in a given year at Johns Hopkins. Suppose, instead of a sample of seven values, we have a sample of 100 birth weights. How should the mean, median, and standard deviation of this sample compare to the same statistics for the sample of seven birth weights?

Question: It is known that the mean diameters of rivets produced by two firms A and B are practically the same but the standard deviations may differ. For 22 rivets produced by firm A, the standard deviation is 2.9 mm. while for 16 rivets manufactured by firm B, the standard deviation is 3-8 mm. Compute the statistic would use to test whether the you products of firm A have the same variability as those of firm B and test its significance?

ou would like to get the highest paying job possible after graduating from UCR and are currently deciding vhether to enroll in ECON 108 in the fall term or not. You find a sample of recent UCR graduates that majc n Economics (there are no double majors in the samples). You sampled 100 Economics majors that took ECON 108 and you find that the average starting salary is 72K dollars, with a sample standard deviation of 10K dollars. You sampled 75 Economics majors that did not take ECON 108 and you find that the average starting salary is 65K dollars, with a sample standard deviation of 15K dollars. Which of the following statements is most correct? O I am not very confident in the results of my hypothesis test because the range in which I fail to reject the null hypothesis is relatively large. O I want to be very confident in the results of my hypothesis test, so the range in which I fail to reject the null hypothesis is relatively large. O The range in which I fail to reject is small, so…

What do you mean by Sample Variance, Sample Standard Deviation,and Standard Error?

A health expert evaluates the sleeping patterns of adults. Each week she randomly selects 40 adults and calculates their average sleep time. Over many weeks, she finds that 5% of average sleep time is less than 3 hours and 5% of average sleep time is more than 3.4 hours. What are the mean and standard deviation (in hours) of sleep time for the population? (Round "Mean" to 1 decimal places and "standard deviation" to 3 decimal places.) Mean Standard deviation

Question of the day: A machine is designed to produce insulating washers for electrical devices of average thickness of 0.025 cm. A random sample of 10 washers was found to have an average thickness of 0.024 cm with a standard deviation of 0.002 cm. Test the significance of the deviation. Value of t for 9 degrees of freedom at 5% level is 2.262?

The reliability of an estimator is assessed in terms of its _____. Select one: a. mean  b. ease of computation c. coefficient of variation d. variance

QUESTION 8 Having an extreme score in a sample (outliers) will NOT effect which of the following?     standard deviation     mean     mode     variance

7. It is well known that car buyers often add accessories to their new cars. A sample of 179 Ottawa purchasers yielded a sample mean of $5000 worth of accessories added to the purchase above the base sticker price. Suppose the cost of accessories purchased for all Ottawa has a standard deviation of $1500. (a) Calculate a 95% confidence interval for the average cost of accessories on Ottawa. - Section Break - (b) Determine the margin of error in estimating the average cost of accessories on Ottawa. (c) What sample size would be required to reduce the margin of error by 50%?

Suppose a baker wants to know, on average, how many pastries they sell in a day. They sampled over 4 days. On the first day they sold 10, on the second day they sold 12, on the third day they sold 18, and on the fourth day they sold 16. The population standard deviation of pastry sales is 3. What is the point estimate (average) number of pastries sold? 26 08 056 O 14 Nex

A quality engineer in charge of a coffee filter pack production line was concerned about the weight (in grams) of the filter packs being produced. The quality team sampled three packs every hour, throughout the production day. The table below shows the results: Sample number 1 2 3 4 5 6 7 20.6 20.1 20.6 21.5 21.4 21.1 21.4 Weight (g) 21.1 20.0 21.2 22.2 21.1 22.3 20.9 20.7 20.3 21.3 21.4 19.9 19.9 21.1

Question 2 In 2015, the average duration of long-distance telephone calls from a certain town was 3.9 minutes. A telephone company wants to perform a test to determine whether this average duration of long- distance calls has changed. Fifty calls, originating from the town, was randomly selected and the following summary minutes. Σx= 205 E(x - x)? = 56.43 a) Calculate the sample mean, &. b) Calculate the sample standard deviation c) Using the p value approach at the 1% level of significance, test whether the mean duration of long-distance calls from the town had increased. d) Construct the 99% confidence interval for the population mean duration of the long-distance calls from the town.

Please see below. Note that the answer IS NOT 60.

Also find the p value and test statistic

Consider the following data: −11,−5,−5,−11,13,−11,−5−11,−5,−5,−11,13,−11,−5 Copy Data Step 2 of 3:  Calculate the value of the sample standard deviation. Round your answer to one decimal place.

A sports shop selects a random sample and records the sales of items made in China and thosemade in America. Country of origin n mean St.Deviation           China 50 22.5 9.75           America 33 33.15 11.6                             What is the SE Mean for the sales from China?

The distribution of annual profit at a chain of stores was approximately normal with mean u = $66,000 and - standard deviation o = $21,000. The executives conducted an audit of the stores with the lowest 20% of profits. What is closest to the maximum annual profit at a store where the executives conducted an audit? Round to the nearest thousand dollar.

The average expenditure on Valentine's Day was expected to be $100.89 (USA Today, February 13, 2006). Do male and female consumers differ in the amounts they spend? The average expenditure in a sample survey of 44 male consumers was $137.38, and the average expenditure in a sample survey of 35 female consumers was $65.11. Based on past surveys, the standard deviation for male consumers is assumed to be $35, and the standard deviation for female consumers is assumed to be $12. The z value is 2.576. Round your answers to  decimal places. b. At 99% confidence, what is the margin of error?  c. Develop a 99%  confidence interval for the difference between the two population means.

Show your work A stenographer claims that she can take dictation at the rate of 120 words per minute. Can we reject her claim on the basis of 100 trials in which she demonstrates a mean of 116 words with a standard deviation of 15 words? Use 5 per cent level of significance.

A political pollster wants to ensure that their poll on attitudes toward separation of church and state gets responses from all major religious groups. What kind of sampling method should be used?

25 An economist would like to test the hypothesis that the average daily screen time that a person spends on mobile devices is greater than 300 minutes. A random sample of 30 smartphone users was selected and their daily screen time was recorded. The standard deviation for the 30 smartphone owners using their devices is 112.19 minutes and the sample mean of the daily screen time is 297.17 minutes. Using a = 0.05, the test statistic of the sample mean is -1.38 -0.138. 0.138 O 1.38

Economic topic. Show your work A weighing machine without any display was used by an average of 320 persons a day with a standard deviation of 50 persons. When an attractive display was used on the machine, the average for 100 days increased by 15 persons. Can we say that the display did not help much? Use a level of significance of 0.05?

Bob Nale is the owner of Nale’s Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 1.80 gallons. From his records, he selects a random sample of 80 sales and finds the mean number of gallons sold is 6.90. What is the point estimate of the population mean? (Round your answer to 2 decimal places.) Develop a 95% confidence interval for the population mean. (Use z Distribution Table.) (Round your answers to 2 decimal places.)