document.write( "Question 1180017: A company installs light bulbs, each with an average life of 7000 hours, standard deviation of 796 hours, and distribution approximated by a normal curve. Find the percentage of the bulbs that can be expected to last more than 8500hours? Round to the hundredth if necessary \n" ); document.write( "
Algebra.Com's Answer #809631 by Theo(13342)\"\" \"About 
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mean is 7000 hours.
\n" ); document.write( "standard deviation is 796 hours.
\n" ); document.write( "z-score = (x - m) / x
\n" ); document.write( "x is the raw score = 8500
\n" ); document.write( "m is the mean = 7000
\n" ); document.write( "s is the standard deviation = 796 hours
\n" ); document.write( "z-score = (8500 - 7000) / 796 = 1.884422111.
\n" ); document.write( "area to the left of that z-score is .9702461149
\n" ); document.write( "area to the right = 1 minus that = .0297538851.
\n" ); document.write( "the percentage of light bulbs that can be expected to last more than 8400 is .0298 rounded to 4 decimal places = 2.98% rounded to 2 decimal places.
\n" ); document.write( "you can use the following calculator to get the same answer.
\n" ); document.write( "https://www.gigacalculator.com/calculators/z-score-calculator.php
\n" ); document.write( "let me know if you have any trouble getting the same results.\r
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