probabilty question (1 Viewer)

[**blu_rose**]

i already put this question up in the study group thread so i'll try mine own as well

agoraphobia is a fear of open spaces which affects 5% of Australian adults. 2 randomly selected Australian adults were asked to complete a survey about fears and phobias. what is the probabilty exactly one of the adults surveyed suffers from agoraphobia?

can someone please help me to get an answer for this im really stuck

the answer is supposed to be 19/200

 

[shafqat]

i already put this question up in the study group thread so i'll try mine own as well

agoraphobia is a fear of open spaces which affects 5% of Australian adults. 2 randomly selected Australian adults were asked to complete a survey about fears and phobias. what is the probabilty exactly one of the adults surveyed suffers from agoraphobia?

can someone please help me to get an answer for this im really stuck

the answer is supposed to be 19/200

there are two possible cases:
you chose someone with agrophobia, and someone without: 1/20.19/20 = 19/400
and then the other way round: 19/20.1/20 = 19/400
so prob = 19/400 + 19/400 = 19/200

 

[withoutaface]

1-1/20*1/20-19/20*19/20

Because the probability of situations where they are both agoraphobes and both non-agoraphobes are (1/20)^2 and (19/20)^2 respectively. We subtract these from 1 and we get the probability of the only other possibility, ie one is, one isnt.

 

[Dreamerish*~]

i already put this question up in the study group thread so i'll try mine own as well

agoraphobia is a fear of open spaces which affects 5% of Australian adults. 2 randomly selected Australian adults were asked to complete a survey about fears and phobias. what is the probabilty exactly one of the adults surveyed suffers from agoraphobia?

can someone please help me to get an answer for this im really stuck

the answer is supposed to be 19/200

draw a tree diagram

--- YES (5/100) --- yes (5/100) --> both affected - 1/400

--- no (95/100) --> one affected - 19/400​

--- NO (95/100) --- yes (5/100) --> one affected - 19/400

--- no (95/100) --> neither affected - 361/400​

19/400 + 19/400 = 19/200

i hope it's clear

 

[**blu_rose**]

u guys are awesome thanks for explaining that for i just hope i remember to do that in my exam

just one question
i'll probably understand it if i think abt it but why do u add 19/400 with itself to get the answer?

 

[FinalFantasy]

u guys are awesome thanks for explaining that for i just hope i remember to do that in my exam

just one question
i'll probably understand it if i think abt it but why do u add 19/400 with itself to get the answer?

it's like
AB and BA
shafqat got AB and den BA and added them cuz it could be 2 possibilities