document.write( "Question 314338: A survey showed that 23% of college students read newspapers on a regular basis and that 83% of college students regularly watch the news on TV. The survey also showed that 21% of college students both follow TV news regularly and read newspapers regularly. \r
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document.write( "(a) What is the probability that a student watches TV news regularly, given that he or she regularly reads newspapers? Round your answer to 2 decimal places.
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document.write( "(b) What is the probability that a randomly selected college student reads newspapers regularly, given that he or she watches TV news regularly? Round your answer to 2 decimal places. \r
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document.write( "
Algebra.Com's Answer #224732 by Edwin McCravy(20060)![]() ![]() You can put this solution on YOUR website! \r\n" ); document.write( "Make this chart: \r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | | | |\r\n" ); document.write( "================================================\r\n" ); document.write( "\r\n" ); document.write( "Fill in 100% in the lower right corner, since all the\r\n" ); document.write( "totals must be 100%:\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( " \n" ); document.write( ">>...A survey showed that 23% of college students read newspapers on a regular basis...<< \n" ); document.write( " \r\n" ); document.write( "So we fill in 23% under the total of the \"read newspapers\" row.\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | | | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( " \n" ); document.write( ">>...83% of college students regularly watch the news on TV...<< \n" ); document.write( " \r\n" ); document.write( "So fill in 83% under the total of the \"Watch TV\" column:\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | | | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( " \n" ); document.write( ">>...21% of college students both follow TV news regularly and read newspapers regularly...<< \n" ); document.write( " \r\n" ); document.write( "So fill in 21% in the space that is both in the \"Watch TV\" column and\r\n" ); document.write( "the Read newspapers row, which is the upper left space:\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( "\r\n" ); document.write( "Now we can fill in the rest of the spaces by subtracting.\r\n" ); document.write( "\r\n" ); document.write( "The number that Read newspapers but don't Watch TV is 2%,\r\n" ); document.write( "since 23%-21% = 2%, so we fill in 2% in the upper middle\r\n" ); document.write( "space:\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | 2% | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | 2% | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( "\r\n" ); document.write( "Since the total who Watch TV is 83%, and 21% both Watch TV and\r\n" ); document.write( "Read newspapers, we subtract 83%-21% = 62% and put that in the\r\n" ); document.write( "space for those who Watch TV and Don't read newspapers:\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | 2% | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | 62% | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( " \r\n" ); document.write( "Sinc 83% total Watch TV, then 100%-83% = 17% total Don't\r\n" ); document.write( "wath TV. So we fill 17% in the total that don't watch TV.\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | 2% | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | 62% | | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | 17% | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( "\r\n" ); document.write( "Sinc 17% total Don't watch TV, then 17%-2% = 15% Don't\r\n" ); document.write( "watch TV and also Don't read newspapers. So we fill 15%\r\n" ); document.write( "in that space:\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | 2% | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | 62% | 15% | |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | 17% | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( "\r\n" ); document.write( "Now finally we have just one more space to fill.\r\n" ); document.write( "And we can fill it either of two ways.\r\n" ); document.write( "\r\n" ); document.write( "1. The total number who Don't read newspapers is\r\n" ); document.write( "the sum 62% + 15% = 77%\r\n" ); document.write( "\r\n" ); document.write( "OR\r\n" ); document.write( "\r\n" ); document.write( "2. Since 100% either read or don't read newspapers,\r\n" ); document.write( "The total number who Don't read newspapers is\r\n" ); document.write( "100%-23% = 77%\r\n" ); document.write( "\r\n" ); document.write( "Since both methods give that same last result 77%, we\r\n" ); document.write( "know we have filled the chart correctly.\r\n" ); document.write( "\r\n" ); document.write( "=================================================\r\n" ); document.write( " | Watch | Don't watch | |\r\n" ); document.write( " | TV | TV | Totals |\r\n" ); document.write( "=================================================\r\n" ); document.write( " Read | | | |\r\n" ); document.write( "newspapers | 21% | 2% | 23% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( "Don't read | | | |\r\n" ); document.write( "newspapers | 62% | 15% | 77% |\r\n" ); document.write( "------------------------------------------------\r\n" ); document.write( " Totals | 83% | 17% | 100% |\r\n" ); document.write( "================================================\r\n" ); document.write( " \r\n" ); document.write( " \n" ); document.write( "(a) What is the probability that a student watches TV news regularly, given that he or she regularly reads newspapers? Round your answer to 2 decimal places. \r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(b) What is the probability that a randomly selected college student reads newspapers regularly, given that he or she watches TV news regularly? Round your answer to 2 decimal places. \r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( "Edwin\n" ); document.write( " |