document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1143106>Question 1143106</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am using Excel as my choice of technology. I am requesting assistance with how to calculate these problems:\r<BR>\n" );
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document.write( "According to the WHO MONICA Project the mean blood pressure for people in China is 128 mmHg with a standard deviation of 23 mmHg (Kuulasmaa, Hense & Tolonen, 1998).  Assume that blood pressure is normally distributed.\r<BR>\n" );
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document.write( "d. Find the probability that a person in China has blood pressure between 120 and 125 mmHg. Used Excel for computation =SUM(0.36399)+(0.55189)-1=-0.084126- the online calculator is giving me positive number but excel is giving me a negative number.\r<BR>\n" );
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document.write( "e.What blood pressure do 90% of all people in China have less than?-How do I even begin to calculate this? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #763878 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=763878\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> from what i can see, .....\r<BR>\n" );
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document.write( "you got the area to the left of a z-score of -.34783 = .363985.<BR>\n" );
document.write( "you got the area to the right of a z-score of -.13043 = .551889.<BR>\n" );
document.write( "you then derived the area to the left of a z-score of -.13043 by taking .551889 - 1 and getting -.448111.<BR>\n" );
document.write( "you did that wrong, because you should have gotten the area to the left of a z-score of -.13043 = 1 - .551889 = .448111.\r<BR>\n" );
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document.write( "your formula was SUM(0.363985)+(0.551889)-1<BR>\n" );
document.write( "if i calculate that out, i get .363985 +.551889 - 1 = -.084126\r<BR>\n" );
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document.write( "when you get the area of the interval, you take the larger area and subtract the smaller area from it.<BR>\n" );
document.write( "in both cases, you get the area to the left of the z-score.<BR>\n" );
document.write( "area to the left of a z-score of -.34783 is .363985<BR>\n" );
document.write( "area to the left of a z-score of -.13043 = .448111.<BR>\n" );
document.write( "you then subtract .363985 from .448111 which becomes .084126.\r<BR>\n" );
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document.write( "sincne the normsdist function give you the area to the left of the z-score, you should have just gotten normsdist(-.34783) = .363985 and normsdist(-.13043) = .448111.<BR>\n" );
document.write( "you then subtract the smaller area from the larger are to get the area in between.\r<BR>\n" );
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document.write( "in your second problem, you want to know the blood pressure that 90% of the people in ch in china have less than.\r<BR>\n" );
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document.write( "you find the z-score that has an area of .9 to the left of it.\r<BR>\n" );
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document.write( "in excel, that would be the using the normsinv formula as shown in the attached excel spreadsheet.\r<BR>\n" );
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document.write( "you would get normsinv(.9 = 1.281552.<BR>\n" );
document.write( "it is telling you that the z-score that has 90% of the area under the normal distribution curve to the left of it is 1.281552.<BR>\n" );
document.write( "you then use that z-score to get the raw score.<BR>\n" );
document.write( "the z-score formula is z = (x - m) / s<BR>\n" );
document.write( "z = 1.281552<BR>\n" );
document.write( "x = x<BR>\n" );
document.write( "m = 128<BR>\n" );
document.write( "s = 23<BR>\n" );
document.write( "you get 1.281552 = (x - 128) / 23<BR>\n" );
document.write( "multiply both sides of this equation by 23 and add 128 to both sides of this equation to get:<BR>\n" );
document.write( "1.281552 * 23 + 128 = x<BR>\n" );
document.write( "solve for x to get x = 157.475696\r<BR>\n" );
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document.write( "what you see in excel will probably be a little different because of differences in rounding, but it should be close to that number.\r<BR>\n" );
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document.write( "there is an online calculator that i use that give you graphical displays of that's going on.\r<BR>\n" );
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document.write( "that calculator can be found at <a  rel=nofollow HREF= \"http://davidmlane.com/hyperstat/z_table.html\" target = \"_blank\">http://davidmlane.com/hyperstat/z_table.html</a>\r<BR>\n" );
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document.write( "with a mean of 128 and a standard deviation of 23, this calculator can tell you the area between 120 and 125 directly as shown below.\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" src = \"http://theo.x10hosting.com/2019/071201.jpg\" alt=\"$$$\" >\r<BR>\n" );
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document.write( "with a mean of 128 and a standard deviation of 23, this calculator can tell you the raw score that has an area of .9 to the left of it as shown below.\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" src = \"http://theo.x10hosting.com/2019/071202.jpg\" alt=\"$$$\" >\r<BR>\n" );
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document.write( "i find excel not as friendly as other tools.<BR>\n" );
document.write( "most of the time i use my TI-84 Plus.\r<BR>\n" );
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document.write( "regardless of what tool you use, you have to keep track of the formulas and the concepts in order to get the right answer.<BR>\n" );
document.write( "area in between 2 z-score is the area to the left of the larger z-score (more positive) minus the area to the left of the smaller z-score (less positive).\r<BR>\n" );
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document.write( " </SPAN>\n" );
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