document.write( "Question 83815: An professor finds that the number of students enrolling in his class is approximated by s(t) = -tsquared + 20t + 80 where t is the number of tests given in one semester.\r
\n" ); document.write( "\n" ); document.write( "(a) How many tests should the professor give so that the number of students enrolling in the class is a maximum?\r
\n" ); document.write( "\n" ); document.write( "(b) If the professor does not want students to enroll, how many tests should he give? \n" ); document.write( "
Algebra.Com's Answer #60285 by stanbon(75887)\"\" \"About 
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An professor finds that the number of students enrolling in his class is approximated by s(t) = -tsquared + 20t + 80 where t is the number of tests given in one semester.
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\n" ); document.write( "Maximum:
\n" ); document.write( "You have a quadratic with a=-1,b=20,c=80
\n" ); document.write( "Max is at t=-b/2a = -20/-2 =10
\n" ); document.write( "# of students will be maximum if he gives 10 tests.
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\n" ); document.write( "No students means s = 0
\n" ); document.write( "-t^2+20t+80=0
\n" ); document.write( "t = [-20+-sqrt(400-4*-1*80]/(-2)
\n" ); document.write( "t = [-20+-sqrt(720)]/-2
\n" ); document.write( "t = [-20+-12sqrt5]/(-2)
\n" ); document.write( "Positive solution:
\n" ); document.write( "t = 23.42
\n" ); document.write( "Rounding down: No students if he gives 23 tests.
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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