Answer to Question 1
P(A B ) = 0.12
Answer to Question 2
If you doubt that the distribution of measurements is bell-shaped, or if you wish for some other reason to be conservative, you can apply Chebyshev's Theorem and be absolutely certain of your statements. Chebyshev's Theorem tells you that at least 3/4 of the measurements fall into the interval from 12.4 to 18.0 and at least 8/9 into the interval from 11.0 to 19.4