document.write( "Question 577439: A man calculated that if his speed had been increased by 4km/h he would have completed his 48km journey 1 hour sooner.determine his speed. \n" ); document.write( "

Algebra.Com's Answer #370170 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A man calculated that if his speed had been increased by 4km/h he would have completed his 48km journey 1 hour sooner.
\n" ); document.write( "determine his speed.
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\n" ); document.write( "Let s = his speed
\n" ); document.write( "then
\n" ); document.write( "(s+4) = his faster speed
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\n" ); document.write( "Write a time equation: time = dist/speed
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\n" ); document.write( "normal time - faster time = 1 hr
\n" ); document.write( " $\"48%2Fs\"$ - $\"48%2F%28%28s%2B4%29%29\"$ = 1
\n" ); document.write( "Multiply by s(s+4)
\n" ); document.write( "s(s+4)* $\"48%2Fs\"$ - s(s+4)* $\"48%2F%28%28s%2B4%29%29\"$ = 1s(s+4)
\n" ); document.write( "cancel the denominators
\n" ); document.write( "48(s+4) - 48s = s^2 + 4s
\n" ); document.write( "48s + 192 - 48s = s^2 + 4s
\n" ); document.write( "0 = s^2 + 4s - 192 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(s-12)(s+16) = 0
\n" ); document.write( "the positive solution
\n" ); document.write( "s = 12 mph his speed
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\n" ); document.write( "Check this by finding the actual times
\n" ); document.write( "48/12 = 4 hrs
\n" ); document.write( "48/16 = 3 hrs
\n" ); document.write( "---------------
\n" ); document.write( "diff is 1 hr
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