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S1 help needed!!! driving me crazy!!

this always happens to me. i get all the other parts of the question, but when it comes to the last part, i DONT even get it.
ok the question is:

the members of a wine tasting club are married couples. for any married couple, the prob of the husband being retired is 0.7
the prob of a wife being retired is 0.4
given that the wife is retired, the probability that the husband is retired is 0.8.
for a randomly chosen married couple who are members of the club, find the prob that:

a) both are retired
b) only one of them is retired
c) neither of them is retired
two married couples are chosen at random
d) find the prob that only one of the two husbands and only one of the two wives is retired.

PLS PLS PLS HELP ME UNDERSTAND THE LAST PART!!!!!!!

Reply 1

IXxi HIIDA ixXI

Draw out the tree diagram, with the first branch being about probability of the husband being retired, and the second branch being about the probability of the wife being retired.

a) 0.7 x 0.4 = 0.28
b) (0.7 x 0.6) + (0.3 x 0.4) = 0.54
c) 0.3 x 0.6 = 0.18
d) 2(0.7 x 0.3) + 2(0.4 x 0.6) = 0.9

(edited 7 years ago)

Reply 2

FAAWAH

Original post by IXxi HIIDA ixXI

I'm afraid that you got them all wrong :frown:

see this is the thing with S1 - i HATE its guts !!!
the answers are: a) 0.32
B) 0.46
C) 0.22
D) 0.2016
sorry should have said the answers in the beginning

Reply 3

IXxi HIIDA ixXI

Original post by papajani1234

I'm afraid that you got them all wrong :frown:

see this is the thing with S1 - i HATE its guts !!!
the answers are: a) 0.32
B) 0.46
C) 0.22
D) 0.2016
sorry should have said the answers in the beginning

I'm going to kill myself