document.write( "Question 918253: 12869The popping-times of the kernels in a certain brand of microwave popcorn are normally distributed with a mean of 150 seconds and a standard deviation of 13 seconds. \r
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document.write( "The first kernel pops 128 seconds after the microwave oven is started. What is the z-score of this kernel? Round your answer to two decimal places. \n" );
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Algebra.Com's Answer #556993 by AlgebraLady88(44)![]() ![]() You can put this solution on YOUR website! The z score is the number of standard deviations from the mean. The formula for this is \r \n" ); document.write( "\n" ); document.write( "z= (sample value - sample mean )/ standard deviation \n" ); document.write( "z= (x-m)/s \n" ); document.write( "z= (128-150)/13 \n" ); document.write( "z= -1.6923077 \n" ); document.write( "z= -1.69 ( to two decimal places)\r \n" ); document.write( "\n" ); document.write( "This shows that the sample 128 secs falls -1.69 standard deviations below the mean. \n" ); document.write( " |