Chapter 7.2, Problem 78E

(a)

To determine

The extent to which the data provided in the question apply to other similar type of workers if all workers for a tunnel construction company are includedin the sample.

(b)

To determine

To find: The difference in the exposure using 95% confidence interval. Also, find the interval and the meaning of 95% confidence. Where, the mean exposure of respirable dust for drill and blast workers is $6.3\text{ mg}{\text{.y/m}}^{\text{3}}$ with standard deviation of $2.8\text{ mg}{\text{.y/m}}^{\text{3}}$ and for outdoor concrete workers the mean exposure of respirable dust is $\text{1}\text{.4 mg}{\text{.y/m}}^{\text{3}}$ with a standard deviation of $0.7\text{ mg}{\text{.y/m}}^{\text{3}}$.

(c)

To determine

To test: The null hypothesis for the exposure of the two type of workers are same also write the Test statistics, the degree of freedom and the P-value.

(d)

To determine

whether the analysis invalid if the distribution provided in the question is skewed.