document.write( "Question 1207570: The lengths of pregnancies in a small rural village are normally distributed with a mean of 266 days and a standard deviation of 17 days.\r
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Algebra.Com's Answer #845517 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "The lengths of pregnancies in a small rural village are normally distributed
\n" ); document.write( "with a mean of 266 days and a standard deviation of 17 days.
\n" ); document.write( "What percentage of pregnancies last beyond 252 days?
\n" ); document.write( "P(X > 252 days) =
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document.write( "A normal distribution curve is a bell shaped curve.\r\n" );
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document.write( "The total area under each such curve is 1.\r\n" );
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document.write( "The percentage of pregnancies that last beyond 252 days, \r\n" );
document.write( "is the area under this normal curve on the right of the raw mark X= 252 days, \r\n" );
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document.write( "You can solve the problem using a regular calculator like TI-83/84.\r\n" );
document.write( "For the given raw mark, such calculators provide the area on the LEFT of the raw mark,\r\n" );
document.write( "Therefore, you should take the COPMPLEMENT to it.\r\n" );
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document.write( "So, for the percentage of pregnancies that last beyond 252 days, \r\n" );
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document.write( "                       z1    z2   mu   SD    <<<---===  formatting pattern\r\n" );
document.write( "     P = 1 - normalcdf(252, 9999, 266, 17).\r\n" );
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document.write( "Here nomalcdf stands for normal cumulative distribution function.\r\n" );
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document.write( "For normalcdf(252, 9999, 266, 17), your calculator will give you the value  P' = 0.2051.\r\n" );
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document.write( "Thus, your final answer is the complement to it  P = 1 - 0.2051 = 0.7949.    ANSWER\r\n" );
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document.write( "Another way to solve the problem is to use an online calculator for normal distribution.\r\n" );
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document.write( "Go to web-site \r\n" );
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document.write( "    https://onlinestatbook.com/2/calculators/normal_dist.html\r\n" );
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document.write( "and use free of charge online calculator there, which is intended for the same purposes.\r\n" );
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document.write( "This online calculator has perfect and intuitively clear interface, so even a beginner student \r\n" );
document.write( "can use it without any difficulties.  Surely, this online calculator will get you the same answer.\r\n" );
document.write( "The calculator shows the area of the interest, so after using it, you will understand the meaning \r\n" );
document.write( "of the procedure in full.\r\n" );
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document.write( "So, choose the option \"Above\" and get the same final probability P = 0.7949 without any trouble \r\n" );
document.write( "about taking the complementary probability.\r\n" );
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