document.write( "Question 111607: The distance traveled by a ball roling down a ramp is given by the equation s(t)=5tsquared, where t is the time after the ball is released, in seconds, and s(t) is mearsured n feet. What is the average speed of the ball for the time t=3 through t=4.5? Express your answer as a decimal to the nearest tenth.\r
\n" ); document.write( "\n" ); document.write( "I came up with s=15 for the 3 second time and s=22.5 for the 4.5 time. I plugged in the number to get 45 seconds and 101.25 seconds and averaged the two. I got an average of 73.125 or 73.1 feet per second. Does that look right?\r
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Algebra.Com's Answer #81403 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
The distance traveled by a ball roling down a ramp is given by the equation
\n" ); document.write( "s(t)=5tsquared, where t is the time after the ball is released, in seconds,
\n" ); document.write( "and s(t) is mearsured n feet. What is the average speed of the ball for the
\n" ); document.write( "time t=3 through t=4.5? Express your answer as a decimal to the nearest tenth.
\n" ); document.write( "I came up with s=15 for the 3 second time and s=22.5 for the 4.5 time. I
\n" ); document.write( "plugged in the number to get 45 seconds and 101.25 seconds and averaged the
\n" ); document.write( "two. I got an average of 73.125 or 73.1 feet per second. Does that look right?
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document.write( "No, sorry.  You averaged the two distances.\r\n" );
document.write( "That is incorrect.\r\n" );
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document.write( "You must use the formula for average speed.\r\n" );
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document.write( "                 Total distance\r\n" );
document.write( "Average speed = ————————————————\r\n" );
document.write( "                   Total time\r\n" );
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document.write( "Notice that in finding the average speed, \r\n" );
document.write( "you do not average anything.  [That sounds\r\n" );
document.write( "like an oxymoron, doesn't it?]\r\n" );
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document.write( "To find the total distance we find \r\n" );
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document.write( "1.  the distance it had traveled in exactly\r\n" );
document.write( "    4.5 seconds, which you correctly found \r\n" );
document.write( "    to be 101.25 feet.\r\n" );
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document.write( "and\r\n" );
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document.write( "2.  the distance it had traveled in exactly \r\n" );
document.write( "    3 seconds, which you also found correctly\r\n" );
document.write( "    as 45 feet.\r\n" );
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document.write( "Then to find the distance it traveled between \r\n" );
document.write( "the instant when 3 seconds had passed and the \r\n" );
document.write( "instant when 4.5 seconds had passed, we subtract\r\n" );
document.write( "the second distance from the first distance, \r\n" );
document.write( "getting \r\n" );
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document.write( "101.25 feet - 45 feet or 56.25 feet which it \r\n" );
document.write( "traveled between 3 and 4.5 seconds.  \r\n" );
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document.write( "So the Total distance = 56.25 feet\r\n" );
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document.write( "Now to find the Total time.  That is simply 4.5 \r\n" );
document.write( "seconds minus 3 seconds or 1.5 seconds\r\n" );
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document.write( "So the total time = 1.5 seconds.\r\n" );
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document.write( "Substituting in \r\n" );
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document.write( "                 Total distance\r\n" );
document.write( "Average speed = ————————————————\r\n" );
document.write( "                   Total time\r\n" );
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document.write( "we get\r\n" );
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document.write( "                 56.25 feet\r\n" );
document.write( "Average speed = —————————————  =  37.5 ft/sec\r\n" );
document.write( "                 1.5 seconds\r\n" );
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document.write( "Edwin
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