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Seventy percent of children who go to the doctor have fevers. Of those with fevers, 30% also have a rash. Of those without fevers, 20% have a rash. What is the probability that a child at the doctor's office with a rash does not have a fever

 Mar 5, 2020
 #1
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For convenience....let there  be  100  children who go to  the doctor.....so...

 

100 * .70  =    70 have fevers

 

70 * .30  =  21 have  fevers  and rash

 

100  - 70  = 30  have no fever

 

30 * .20  =  6  have  no fever  but  have a rash

 

21  + 6  =   27  have  rashes

 

So

 

6  have  a rash  but  no fever

_______________________  =   6  / 27   =   2 / 9

27    have a rash

 

 

EDIT.....thanks, Geno forspotting my earlier error   !!!

 

cool cool cool

 Mar 5, 2020
edited by CPhill  Mar 5, 2020
edited by CPhill  Mar 5, 2020

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