document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=874530>Question 874530</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose the life of a particular brand of calculator battery is normally distributed with a mean of 80 hours and a standard deviation of 11 hours. <BR>\n" );
document.write( "a. what is the probability that a single battery randomly selected from the population will have a life of 75 to 85 hours? .3506<BR>\n" );
document.write( "b. what is the probability that 9 randomly sampled batteries from the population will have a mean life of between 75 and 85 hours? .8274<BR>\n" );
document.write( "c. if the manufacturer of the battery is able to reduce the standard deviation of battery life of 11 to 9 hours . what would be the probability that 9 batteries randomly sampled from the population will have a sample mean life of 75 and 85 hours?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #527552 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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/cgi-bin/show-face.mpl?user=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=527552\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> c. z = ±  5/ (9/sqrt(9) = 5/3<BR>\n" );
document.write( ".9522 - .0478 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );