1, A = ~ 2 people from community a, B = ~ 2 people from community b, C = ~ 2 people from community a, 1 people from community b,

M = (2) Everyone is a low-carbon person.

P = P(A)P(A | M)+P(B)P(B | M)+P(C)P(C | M)

= 1/6 ﹙ 1/2﹚? + 1/6 ﹙4/5﹚? +2×2/6 ﹙ 1/2﹚ ﹙4/5﹚

= 137/300

2、25*[ 1—( 1/2)*( 1—20%)*( 1—20%)]= 17