Search & Filtering
the following are the results of extension tests carried out on two types of yarn(percentage extension at break). yarn A: 14.1,14.7,15.1,14.3,15.6,14.8 and yarn B: 16.9,16.3,15.9,15.7,15.7. do these results suggest that one yarn is significantly more extensible than the other?
describe the F-tests used for testing equality of the variation of the two different populations. if ten ring bobbins are selected from the day shift and night shift productions have shown standard deviations of the count as 1.2 and 2.2 units respectively. can we say that variation in count is more for the night shift production than that of day shift production?
according to textile engineering, an important property of fiber is its water absorbency. the average percent absorbency of 25 randomly selected pieces of cotton fiber was found to be 20 with standard deviation of 1.5. a random sample of 25 pieces of acetate yielded an average percent of 12 with a standard deviation of 1.25. is there strong evidence that the population mean percent absorbency is significantly higher for cotton fiber than acetate? assume that the percent absorbency is approximately normally distributed and that the population variances in percent absorbency for the two fibers are the same. use a significant level of 0.05.
Estimation and Confidence Intervals
The Greater Pittsburgh Area Chamber of Commerce wants to estimate the mean time workers who are employed in the downtown area spend getting to work. A sample of 15 workers reveals the following number of minutes spent traveling.
29, 38, 38, 33, 38, 21, 45, 34, 40, 37, 37, 42, 30, 29, 35
Requirements:
i) Develop a 90%, 95% and 98 percent confidence interval for the population mean?
ii) Compare and interpret the result?
- a supplier submits lots of fabric to a textile manufacturer. the customer wants to know if the lot average breaking strength exceeds 200 psi. if so, she wants to accept the lot. past experience indicates that a reasonable value for the variance of breaking strength is 100(psi)2. four specimens are randomly selected, and the average breaking strength observed is y=214 psi. is the customer accepting this lot at alpha=0.05?
The modal interval can be determined when making a histogram and adjusting the size of thebintervals
even A and B are such that P(A U B )=0.76,P(B)=0.4 Given that A and B are non mutually exclusive events that are independent calculate P(A)
Given that P(A)=0.7,P(B)= and P (A and B)=0.35
. You are working in an organisation were you are concerned about customer complaints. You make an observation and think that customers are also leaving your organisation for your competitors. You want to determine if there is a correlation (a relationship between your 𝑥𝑥 and 𝑦𝑦 variables) between customer complaints and customers leaving the organisation. You obtain the following quantitative data for complaints received and customers leaving. Let your independent variable be complaints received and your dependent variable be customers lost and construct a linear regression. Graph your linear regression on a Cartesian Plane (using for example, Excel or graph paper) and give a brief interpretation for your result.
Page 81 of 81 Complaints
23
34
56
7
41
9
48
3
5
17
Customers Lost
11
13
30
5
18
6
24
6
4
21
3. The owner of a cell phone store at Greenhill Shopping Center was not happy when he learned that the
average number of cell phones sold daily was only 8 mobile phones. He hired a new seller and told him to
tally the daily sales for 20 days. The following are the number of cell phones sold for the past 20 days.
9
11
12
6
12
8
17
14
10
12
11
18
15
14
17
Does the collected data present sufficient evidence to indicate that the average number of cell phones sold
daily has increased? Use 0.05 level of significance. Assume normality in the population.
