document.write( "Question 1167859: Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0°C and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested. Find P81, the 81-percentile. This is the temperature reading separating the bottom 81% from the top 19%.
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Algebra.Com's Answer #852105 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0°C
\n" ); document.write( "and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested.
\n" ); document.write( "Find P81, the 81-percentile. This is the temperature reading separating the bottom 81% from the top 19%.
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document.write( "To solve the problem, we should translate this set of words into meaningful human form.\r\n" );
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document.write( "We are given the normal curve with the mean value of 0 and the standard deviation of 1.\r\n" );
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document.write( "They want you find the score 'x' (the temperature) such that the area under this normal curve \r\n" );
document.write( "on the left of 'x' be 0.81.\r\n" );
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document.write( "Use the standard function invNorm of a regular hand calculator TI-84/87.\r\n" );
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document.write( "Its format is\r\n" );
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document.write( "    x = invNorm(area, mean, SD).\r\n" );
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document.write( "So, in this problem we want to calculate  invNorm(0.81, 0, 0.81).\r\n" );
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document.write( "The calculator gives the  ANSWER  x = 0.8779.\r\n" );
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document.write( "It means that 87.79% of readings will be lower than 0.81 °C.\r\n" );
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document.write( "Alternatively, you may use the Excel function NORM.INV(area,mean,SD) \r\n" );
document.write( "or online free of charge calculator at this web-page\r\n" );
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document.write( "https://onlinestatbook.com/2/calculators/inverse_normal_dist.html\r\n" );
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document.write( "This online calculator has an advantage showing you visually the area under the curve,\r\n" );
document.write( "so you will learn the subject momentarily and better than if 5 or 15 teachers/tutors\r\n" );
document.write( "will explain it to you.\r\n" );
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document.write( "With this online calculator, you will catch the problem instantly.\r\n" );
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