Exercise 2 114 p9 for the following types of values

Exercise 2 (1.14, p.9):
For the following types of values, designate discrete variables (D) and continuous
variables (C): (a) Number of units of an item held in stock, (b) ratio of current assets
to current liabilities, (c) total tonnage shipped, (d) quantity shipped, in units, (e)
volume of traffic on a toll road, ( f ) attendance at the company’s annual meeting.
Explain each item!
Exercise 3 (1.7, p.6):
For the purpose of statistical inference a representative sample is desired. Yet, the
methods of statistical inference require only that a random sample be obtained.
Why?
Explain in your own words.