document.write( "Question 181936This question is from textbook
\n" ); document.write( ": What is the probability of a seven-digit (7) phone number containing the number seven (7)? \n" ); document.write( "

Algebra.Com's Answer #136564 by josmiceli(19441) $\"\"$ $\"About$

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When you want the probability of a OR b OR c ...etc, you musrt
\n" ); document.write( "add the probabilities of each event occurring separately
\n" ); document.write( "The 1st digit can be 1-9 (0 is not allowed)
\n" ); document.write( "The probability of it being a $\"7\"$ is $\"1%2F9\"$
\n" ); document.write( "The rest of the digits can be 0-9, so their probability is $\"1%2F10\"$
\n" ); document.write( "The proibability of 1 number being a $\"7\"$ is then:
\n" ); document.write( " $\"%281%2F9%29+%2B+6%2A%281%2F10%29\"$
\n" ); document.write( " $\"%281%2F9%29+%2B+6%2A%281%2F10%29+=+10%2F90+%2B+54%2F90\"$
\n" ); document.write( " $\"10%2F90+%2B+54%2F90+=+64%2F90\"$
\n" ); document.write( " $\"64%2F90+=+32%2F45\"$ answer \n" ); document.write( "

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