document.write( "Question 1173518: Find the z-score that corresponds to the following areas.
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document.write( "Area to the left is 1.24
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Algebra.Com's Answer #798764 by Theo(13342)![]() ![]() You can put this solution on YOUR website! with normal distributions, the total area is 1 and anything else has to be between 0 and 1. \n" ); document.write( "if we assume you are talking in percents, then the total area is 100% and 1.24% / 100% would be equal to .0124. \n" ); document.write( "the z-score with an area of .0124 to the left of it would be equal to -2.244503871. \n" ); document.write( "round this to 3 decimal places and it becomes -2.245.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i used my ti-84 plus scientific calculator to get the more detailed answer.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the tables and the calculators assume that the area is a ratio of the area to the left of the z-score divided by the whole area under the normal distribution curve. \n" ); document.write( "the whole area under the normal distribution curve is assumed to be equal to 1. \n" ); document.write( "that's why they show the area to the left of a z-score as a ratio between 0 and 1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's a reference on z-score tables and how to find the area to the left of the z-score.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "https://mathbitsnotebook.com/Algebra2/Statistics/STzScores.html#:~:text=To%20find%20a%20specific%20area,on%20a%20standard%20normal%20distribution.&text=You%20need%20both%20tables!\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "most tables are full tables, so concentrate on that.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the table i normally reference can be found at https://www.math.arizona.edu/~rsims/ma464/standardnormaltable.pdf\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "using that table, i found that the z-score of -2.24 gave an area of .01255 to the left of it and the z-score of -2.25 gave an area of .01222 to the left of it. \n" ); document.write( ".0124 was in between z-score of -2.24 and -2.25.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i manually interpolated to get a z-score of -2.2445 which is equal to -2.245 when rounded to 3 decimal places.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "whether i used my ti-84 plus calculator, or used the table and manually interpolated, i got a z-score of -2.245 rounded to 3 decimal places. \n" ); document.write( "that's usually close enough.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "a calculator you can use online can be found at https://stattrek.com/online-calculator/normal.aspx\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "using that calculator, i got a z-score of -2.245 with a lot less work than manual interpolation.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |