document.write( "Question 1090706: The manager of Ardmore Pharmacy knows that 25% of the customers entering the store buy prescription drugs, 65% buy over-the-counter drugs and 18% buy both types of drugs. What is the probability that a randomly selected customer will buy at least one of these two types of drugs? \n" ); document.write( "
Algebra.Com's Answer #705144 by mathmate(429)\"\" \"About 
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Question:
\n" ); document.write( "The manager of Ardmore Pharmacy knows that 25% of the customers entering the store buy prescription drugs, 65% buy over-the-counter drugs and 18% buy both types of drugs. What is the probability that a randomly selected customer will buy at least one of these two types of drugs?
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\n" ); document.write( "Solution:
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\n" ); document.write( "METHOD A
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\n" ); document.write( "Step 1:
\n" ); document.write( "Draw a Venn diagram with two overlapping circles A & B.
\n" ); document.write( "Label A with 65%, and B with 25%.
\n" ); document.write( "The overlapped area is 18%.
\n" ); document.write( "Step 2:
\n" ); document.write( "Calculate the percentage of the total area covered by the two circles, noting that
\n" ); document.write( "- Non-overlapping area of A = 65-18=47%
\n" ); document.write( "- non-overlapping area of B = 25-18=7%
\n" ); document.write( "Step 3:
\n" ); document.write( "Interpret and conclude the total area covered by A & B, meaning the total percentage covered represents the percentage of customers who buy either prescription or over-the-counter (OTC) drugs, or both.
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\n" ); document.write( "Method B:
\n" ); document.write( "Use the relationship between union and intersection of two sets:
\n" ); document.write( "P(A∪B)=P(A)+P(B)-P(A∩B)=65%+25%-18%=72% \n" ); document.write( "
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