document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1109338>Question 1109338</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The lengths of pregnancies are normally distributed with a mean of 270 days and a standard deviation of 15 days. a. Find the probability of a pregnancy lasting 309 days or longer. b. If the length of pregnancy is in the lowest 4&#8203;%, then the baby is premature. Find the length that separates premature babies from those who are not premature.<BR>\n" );
document.write( " I have a TI-84 but im not sure how to solve  </SPAN>\n" );
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document.write( " The lengths of pregnancies are normally distributed with a mean of 270 days and a standard deviation of 15 days. a. Find the probability of a pregnancy lasting 309 days or longer. b. If the length of pregnancy is in the lowest 4&#8203;%, then the baby is premature. Find the length that separates premature babies from those who are not premature.<BR>\n" );
document.write( "I have a TI-84 but im not sure how to solve <BR>\n" );
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document.write( "a) z(309) = (309-270)/15 = 2.6<BR>\n" );
document.write( "P(x > 309) = P(z > 2.6) = normalcdf(2.6,100) = 0.0047<BR>\n" );
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document.write( "b) Find the z-value with a left tail of 0.04<BR>\n" );
document.write( "invNorm(0.04) = -1.7507<BR>\n" );
document.write( "Find the corresponding # of days::<BR>\n" );
document.write( "d = z*s+u<BR>\n" );
document.write( "d = -1.7507*15+270 = 243.74 days<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( "</TD></TR></TABLE>\n" );