document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1182850>Question 1182850</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A smart phone manufacturer is interested in constructing a 95% confidence interval for the proportion of smart phones that break before the warranty expires.<BR>\n" );
document.write( "90 of the 1594 randomly selected smart phones broke before the warranty expired.\r<BR>\n" );
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document.write( "a. With 95% confidence the proportion of all smart phones that break before the warranty expires ______ and ______.\r<BR>\n" );
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document.write( "b. If many groups of 1594 randomly selected smart phones are selected, then a different confidence interval would be produced for each group.<BR>\n" );
document.write( "About ________ percent of these confidence intervals will contain the true population proportion of all smart phones that break before the warranty expires and about _______ percent will not contain the true population proportion.   </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #812963 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=812963\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> p hat is 90/1594=0.0565<BR>\n" );
document.write( "half-interval is z(0.975)*sqrt(phat*(1-phat)/n)<BR>\n" );
document.write( "=1.96*sqrt(0.0565*0.9435/1594)<BR>\n" );
document.write( "=0.0113<BR>\n" );
document.write( "the interval is (0.0452, 0.0678)<BR>\n" );
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document.write( "About 95% of the CI would contain the true pop. proportion and about 5% would not. One would not know which 95 and 5, however.  </SPAN>\n" );
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