document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1181874>Question 1181874</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The systolic blood pressure (BP) of adults in the USA is nearly normally distributed with a mean of 120 and standard deviation of 20 .\r<BR>\n" );
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document.write( "Someone qualifies as having Stage 2 high blood pressure if their systolic blood pressure is 160 or higher.\r<BR>\n" );
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document.write( "(a) Around what percentage of adults in the USA have stage 2 high blood pressure? Give your answer rounded to two decimal places.\r<BR>\n" );
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document.write( "____________ %\r<BR>\n" );
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document.write( "(b) Stage 1 high BP is specified as systolic BP between 140 and 160. What percentage of adults in the US qualify for stage 1? Give your answer rounded to two decimal places.\r<BR>\n" );
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document.write( "_____________ %\r<BR>\n" );
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document.write( "(c) Your doctor tells you that you are in the 30th percentile (e.g. bottom 30%) for blood pressure among US adults. What is your systolic BP? Give your answer <BR>\n" );
document.write( "rounded to two decimal places.\r<BR>\n" );
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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 #811820 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=811820\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a. This is asking what percentage are 2 std. deviations above the mean, and that is about 2.5%.Normalcdf(2,6) is 2.28%.  The 6 is large enough for the top number. One may use 1e99, but 6 works as well.<BR>\n" );
document.write( "b. This is asking what percentage are between 1 and 2 sd, and that his 16-2.5 or about 13.5%. The actual amount can be found using 2ndVARS2 normal cdf (1,2) and is 13.59%.<BR>\n" );
document.write( "c. z(0.30) is infvnorm(0.30,0,1) or -0.5244<BR>\n" );
document.write( "-0.5244=(x-120)/20<BR>\n" );
document.write( "-10.49=x-120<BR>\n" );
document.write( "x=109.51 mm Hg<BR>\n" );
document.write( "(medical note: unless this is done intra-arterially, the error is at least a few mm Hg from different ears or from even the same person a few seconds later hearing it). </SPAN>\n" );
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