document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=107512>Question 107512</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am trying to help my daughter with her homework, but since I have no idea what I am doing I hope that having the answer will help me out:\r<BR>\n" );
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document.write( "Cricket Problem:  Based on information in Deep River Jim's Wilderness Trailbook, the rate at which crickets chirp is a lenear function of temperature.  At 55 degrees F they make 70 chirps per minute and at 69 degrees F they make 126 chirps per minute.<BR>\n" );
document.write( "a)  Write the equation expressing chirping rate as a function of temperature.<BR>\n" );
document.write( "b)  Predict the chirping rate at 90 degrees F.<BR>\n" );
document.write( "c)  How warm is it if they are chirping 120 chirps per minute?<BR>\n" );
document.write( "d)  Calculate the temperature-intercept.  What does this tell you about this numbeer in the real-world?<BR>\n" );
document.write( "e)  Calculate the chirping-intercept.  What does the chirping-intercept tell you about the real-worl?<BR>\n" );
document.write( "f)  Shetch and label the graph.\r<BR>\n" );
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document.write( "Thank you for any help.<BR>\n" );
document.write( "Brian </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #78287 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=78287\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Cricket Problem: Based on information in Deep River Jim's Wilderness Trailbook, the rate at which crickets chirp is a lenear function of temperature. At 55 degrees F they make 70 chirps per minute and at 69 degrees F they make 126 chirps per minute.<BR>\n" );
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document.write( "You have two points: (55,70) and (69,126)<BR>\n" );
document.write( "a) Write the equation expressing chirping rate as a function of temperature.<BR>\n" );
document.write( "slope = [126-70]/[69-55] = 56/14 = 4<BR>\n" );
document.write( "chirps = slope(temp) + b<BR>\n" );
document.write( "Substitute chirps=70,temp=55,slope=4 to solve for \"b\":<BR>\n" );
document.write( "70 = 4(55)+b<BR>\n" );
document.write( "b = -150<BR>\n" );
document.write( "EQUATION: chirps = 4(temp)-150<BR>\n" );
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document.write( "b) Predict the chirping rate at 90 degrees F.<BR>\n" );
document.write( "chirps = 4*90-150<BR>\n" );
document.write( "chirps = 360-150<BR>\n" );
document.write( "chirps = 210<BR>\n" );
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document.write( "c) How warm is it if they are chirping 120 chirps per minute?<BR>\n" );
document.write( "120 = 4*temp - 150<BR>\n" );
document.write( "270 = 4*temp<BR>\n" );
document.write( "temp = 135/2 = 67.5 degrees<BR>\n" );
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document.write( "d) Calculate the temperature-intercept. What does this tell you about this number in the real-world?<BR>\n" );
document.write( "temp-intercept = -150<BR>\n" );
document.write( "It is unrealistic as it occurs when the termperature is zero.<BR>\n" );
document.write( "Of course there are no crickets around when the temp is zero.<BR>\n" );
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document.write( "e) Calculate the chirping-intercept. What does the chirping-intercept tell you about the real-world?<BR>\n" );
document.write( "nothing<BR>\n" );
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document.write( "f) Shetch and label the graph.<BR>\n" );
document.write( "Plot the two points and draw a line thru them.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28400%2C300%2C-10%2C100%2C-160%2C160%2C4x-150%29 ALIGN=MIDDLE  ALT=\"graph%28400%2C300%2C-10%2C100%2C-160%2C160%2C4x-150%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( " <BR>\n" );
document.write( " </SPAN>\n" );
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