Please help me by answering the following questions:
The strengths are expressed in pounds. Does the difference in mean strengths indicate a real difference in the mean strengths of the yarn?
- From the following data compute quartile deviation and the coefficient of skewness:
| Size | 5 – 7 | 8 – 10 | 11 – 13 | 14 – 16 | 17 – 19 |
| Frequency | 14 | 24 | 38 | 20 | 4 |
- A bank has a test designed to establish the credit rating of a loan applicant. Of the persons, who default (D), 90% fail the test (F). Of the persons, who will repay the bank (ND), 5% fail the test. Furthermore, it is given that 4% of the population is not worthy of credit; i.e., P(D) = .04. Given that someone failed the test, what is the probability that he actually will default (When given a loan)?
- Strength tests carried out on samples of two yarns spun to the same count gave the following results:
| | Number in sample | Sample Mean | Sample variance |
| Yarn A | 4 | 50 | 42 |
| Yarn B | 9 | 42 | 56 |
The strengths are expressed in pounds. Does the difference in mean strengths indicate a real difference in the mean strengths of the yarn?