Have them try and conceive situation so that it supports thinking about the questions in probabilistic terms.

Want them to imagine repeatedly sampling one element at a time from a population until a representative sample has been collected . Ask: what is the population here? (a collection of crime statistic); What is the composition of that population (think of 11,717 slips of paper each of which has written on it three things (RA, RV, DI))

Perhaps use tree diagram to show composition of population.

Stress that when sample has been collected we expect it to resemble population in its composition.

Notation: stress that P[(w, nw, f)] should be interpreted as " if you select an element from population repeatedly at random, what fraction of the time do you expect to get outcome (w, nw, f)

Ask: does anyone see a relationship between questions 3 & 4 and the kind of question asked in the drug test situation of last week?

Think about these questions as restricting that part of the pop/sample we are looking at. So once we have sample, re-organize it and look at only a part (of interest) of it.

4. Have ActivStats open on computers. Have students go to computers and go through Section 14-1 demo 1 only (this introduces them to the notation for conditional probability), then activity 4. In the activity have them not only answer the questions but also:

(2) re-phrase questions in probabilistic terms. That is, say how the symbol P[A|B] should be interpreted so that it refers to a probabilistic situation. This includes expressing this interpretation with use of words other than "given" or "condition".