Given that a and b are real numbers such that -3 ≤ a ≤ 2 and -1 ≤ b ≤ 4, and values for a and b are chosen at random, what is the probability that product a*b is positive?
+23252 Translate -3 <= a <= 2 into -3 <= x <= 2 and -1 <= b <= 4 into -1 <= y <= 4
and place this region onto a regular x-y plane.
The total region covered is 5 · 5 = 25 square units.
The positive product region is (2 · 4) + (-3 · -1) = 8 + 3 = 11 square units.
The probability of landing on the positive region is 11 / 25.
