document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=849900>Question 849900</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi, \r<BR>\n" );
document.write( "\n" );
document.write( "I needed help with the following:\r<BR>\n" );
document.write( "\n" );
document.write( "The number of minutes per week that students spend surfing the internet is normally distributed with a mean of 490 minutes and standard deviation of 42 minutes.Calculate the probability that the time, in a week, a student spends surfing the internet is									<BR>\n" );
document.write( "									<BR>\n" );
document.write( "1)	more than 500 minutes							to 4 dp	<BR>\n" );
document.write( "									<BR>\n" );
document.write( "2)	less than 440 minutes							to 4 dp	<BR>\n" );
document.write( "									<BR>\n" );
document.write( "3)	less than 555 minutes							to 4 dp	<BR>\n" );
document.write( "									<BR>\n" );
document.write( "4)	between 500 and 555 minutes						0.5342	to 4 dp	<BR>\n" );
document.write( "									<BR>\n" );
document.write( "5)	between 440 minutes and 555 minutes.						to 4 dp	<BR>\n" );
document.write( "									<BR>\n" );
document.write( "6)	Given that 67% of students spend less than M minutes,								<BR>\n" );
document.write( "	calculate the value of M, correct to 1 decimal place.				to 1 dp	<BR>\n" );
document.write( "		\r<BR>\n" );
document.write( "\n" );
document.write( "Thank You.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #511830 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=511830\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The number of minutes per week that students spend surfing the internet is normally distributed with a mean of 490 minutes and standard deviation of 42 minutes.Calculate the probability that the time, in a week, a student spends surfing the internet is \r<BR>\n" );
document.write( "\n" );
document.write( "1) more than 500 minutes to 4 dp<BR>\n" );
document.write( "z(500) = (500-490)/42 = 10/42<BR>\n" );
document.write( "P(x > 500) = P(z > 10/42) = normalcdf(10/42,100) = 0.4059<BR>\n" );
document.write( "--------------------------------------------------------------<BR>\n" );
document.write( "2) less than 440 minutes to 4 dp<BR>\n" );
document.write( "Same procedure using z(440) = (440-490)/42 = -50/42<BR>\n" );
document.write( "------<BR>\n" );
document.write( "3) less than 555 minutes to 4 dp<BR>\n" );
document.write( "same \r<BR>\n" );
document.write( "\n" );
document.write( "4) between 500 and 555 minutes  to 4 dp<BR>\n" );
document.write( "z(555)=(555-490)/42 = 65/42<BR>\n" );
document.write( "Etc.<BR>\n" );
document.write( "----------------------- \r<BR>\n" );
document.write( "\n" );
document.write( "5) between 440 minutes and 555 minutes. to 4 dp<BR>\n" );
document.write( "Find P(-50/42< z < 65/42) = normalcdf(-50/42,65/42) = 0.7863<BR>\n" );
document.write( "=====================<BR>\n" );
document.write( "The number of minutes per week that students spend surfing the internet is normally distributed with a mean of 490 minutes and standard deviation of 42 minutes.Calculate the probability that the time, in a week, a student spends surfing the internet is \r<BR>\n" );
document.write( "\n" );
document.write( "1) more than 500 minutes to 4 dp \r<BR>\n" );
document.write( "\n" );
document.write( "2) less than 440 minutes to 4 dp \r<BR>\n" );
document.write( "\n" );
document.write( "3) less than 555 minutes to 4 dp \r<BR>\n" );
document.write( "\n" );
document.write( "4) between 500 and 555 minutes 0.5342 to 4 dp \r<BR>\n" );
document.write( "\n" );
document.write( "5) between 440 minutes and 555 minutes. to 4 dp \r<BR>\n" );
document.write( "\n" );
document.write( "6) Given that 67% of students spend less than M minutes, <BR>\n" );
document.write( "calculate the value of M, correct to 1 decimal place. to 1 dp <BR>\n" );
document.write( "Find the z-value with a left-tail of 0.67::<BR>\n" );
document.write( "invNorm(0.67) = 0.4399<BR>\n" );
document.write( "Find M = 0.4399*42+500 = 518.48<BR>\n" );
document.write( "---------------------------<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );