1) You intend to purchase the electric toothbrush. There is display at store which contains 15 of these items. You choose toothbrushes at random with no replacement. Unbeknownst to you or store, 3 are defective. Find out the probability that:
a) First electric brush chosen is defective?
b) First 2 brushes selected are defective?
c) First 3 brushes selected are defective?
d) First 3 brushes selected work properly?
e) What rule(s) of probability does this question illustrate?