Question

How do you make a tree diagram for this? (and in general)
1) of the voters in a certain city, 40% are republicans and 60% are democrats. among the republicans, 70% are in favor of a particular bond issue whereas 80% of the democrats favor the issue. if a voter is selected at random in the city, what is the probability that he or she will favor the bond issue?

Answer 1

can someone check this answer i got. i got 37/250.
two branches are republican and democrat.
from republican two branches are favor and dislike. probability of being republican 40/100 and probability of favoring issue is 70/100 and disliking is 30/100
from democrat two branches are favor and dislike. probability of being democrat is 60/100. probability of favoring issue is 80/100 and disliking is 20/100.

Math:
P(Republican and favor)=40/100 x 70/100 = 280/10000 = 7/250
P(Democrat and favor)=60/100 x 20/100 = 1200/10000 = 3/25
Favor= P(Rep. and favor) + P(Dem. and favor)
7/250 + 3/25 = 37/250