1. Someone can take two from a bag with two pieces 100 and three pieces of 50, so that he can get the expectation of money? The answer is 140.

Event 1: if both are 100 yuan (* * 200 yuan), then p1= c22/c52 =110;

Event 2: Two tickets from 50 yuan (*** 100 yuan), then P2 = C32/C52 = 3/10;

Event 3: one is 100 yuan and the other is 50 yuan (*** 150 yuan), so P3 = C21C31/C52 = 6/10;

So the mathematical expectation of the amount of money he got is (p1) * 200+(p2) *100+(P3) *150 = 20+30+90 =140 yuan;

2. solution: draw lots, the probability is 4/7 of 1/7 is 0, 2/7 is-1, and the expected value of each draw is (p1) *1+(p2) * 0+.