document.write( "Question 1076540: The volume, L litres, of emulsion paint in a plastic tub may be assumed to be normally distributed with mean 10.25 and variance s2.
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document.write( "(a) Assuming that s2 0.04, determine P(L<10) \n" );
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Algebra.Com's Answer #691167 by Theo(13342) You can put this solution on YOUR website! the volume is a normal distribution with mean = 10.25 and variance = s^2 (?)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if s^2 = .04, then s = sqrt(.04) = .2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "s is the standard deviation.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you have:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "m =10.25 \n" ); document.write( "s = .2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you want to find the probability of the number of liters being 10 or less.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you calculate the z-factors as follows:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "z = (x-m)/s\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "z is the z-factor \n" ); document.write( "x is the raw score \n" ); document.write( "m is raw mean \n" ); document.write( "s is the standared deviation\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you get z = (10 - 10.25) / .2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for z to get z = -.25 / .2 = -.125\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "use a z-score calculator or a z-score table to find the area to the left of a z-score of -.125.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i used the the following calculator.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "http://stattrek.com/online-calculator/normal.aspx\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i used the following table.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "http://www.stat.ufl.edu/~athienit/Tables/Ztable.pdf\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i entered a z-score of -.125. \n" ); document.write( "the mean is and the standard deviation is 1 for a z-score. \n" ); document.write( "the calculator then told me that the probability of getting a z-score to the left of that (less than that) was .45026\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the calculator told me that the probability of a z-score being less than -.125 is .45026\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "with the table, i had to do a little interpolating.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this is because the table only goes to 2 decimal places.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i looked for the probability to the left of -.12 and to the left of -.13.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "a z-score of -.12 gave an area to the left as .4522.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "a z-score of -.13 gave an area to the left as .4483.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since -.125 is roughly in between, then i calculated that the probability would be .45025\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the calculator is more accurate than interpolation because interpolation is straight line while the actual values in between are more on a curve.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's a picture of what the calculator shows:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's a picture of what the correct row on the table shows:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "in the table, the first column gets you to the row that contains a z-score of -.1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's one decimal place accuracy only.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "on that same row, the third column gets you the area to the left of a z-score of -.12 and the fourth column gets you to the area to the left of a z-score of -.13.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's twodecimal place accuracy only.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you then interpolate to get the area to the left of a z-score of -.125\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |