document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=923600>Question 923600</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Assume that on a standardized test of 100 questions, a person has a probability of 80% of answering any particular question correctly. Find the probability of answering between 70 and 80 questions, inclusive, correctly.<BR>\n" );
document.write( " P(70 &#8804; X &#8804; 80)=? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #560171 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=560171\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Assume that on a standardized test of 100 questions, a person has a probability of 80% of answering any particular question correctly. Find the probability of answering between 70 and 80 questions, inclusive, correctly.<BR>\n" );
document.write( " P(70 &#8804; X &#8804; 80)=?<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "mean = np = 100*0.8 = 80<BR>\n" );
document.write( "std = sqrt(npq) = sqrt(80*0.20) = 4<BR>\n" );
document.write( "-------------------------<BR>\n" );
document.write( "z(70) = (70-80)/4 = -5/2<BR>\n" );
document.write( "---<BR>\n" );
document.write( "z(80) = 0<BR>\n" );
document.write( "-----------------<BR>\n" );
document.write( "P(7<= x <=80) = P(-5/2)<= z <= 0) = 0.49<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "=============== </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );