document.write( "Question 711148: A vaccine has a 90% probability of being effective in preventing a certain disease. the probability of getting a certain disease if a person is not vaccinated is 50%. In a certain geographic region, 25% of the people get vaccinated. If a person is selected at random, find the probability that he or she will contract the disease. \n" ); document.write( "
Algebra.Com's Answer #437306 by srinivas.g(540)\"\" \"About 
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% of the people vaccinated = 25%
\n" ); document.write( " But vaccine has a 90% probability of being effective in preventing a certain disease.
\n" ); document.write( " % probability not being effective = 10 %
\n" ); document.write( " % people may get disease = 25% * 10% = 2. 5%
\n" ); document.write( " 75 % of the people has not vaccinated
\n" ); document.write( "the probability of getting a certain disease if a person is not vaccinated is 50%
\n" ); document.write( " % people may get disease = 75 % * 50 %
\n" ); document.write( " = 37.5 %
\n" ); document.write( " total % of people may get disease = 37.5 %+ 2.5 %
\n" ); document.write( " = 40 %
\n" ); document.write( " so 0ut 0f 100 people , 40 people may get disease
\n" ); document.write( " Hence If a person is selected at random, find the probability that he or she will contract the disease is 40 / 100
\n" ); document.write( " =4/10
\n" ); document.write( " =2/5 or simply 40 % \n" ); document.write( "
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