document.write( "Question 687161: Of randomly selected students with random variable x with normal distribution.
\n" ); document.write( "12.10% score below 60 and 6.3% score above 95.
\n" ); document.write( "I have to find µ = E[X] and σ^2 = Variance (X). \r
\n" ); document.write( "\n" ); document.write( "I have no idea what to do with this at all please help. \n" ); document.write( "
Algebra.Com's Answer #425121 by stanbon(75887)\"\" \"About 
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Of randomly selected students with random variable x with normal distribution.
\n" ); document.write( "Draw a normal curve.\r
\n" ); document.write( "\n" ); document.write( "12.10% score below 60 and 6.3% score above 95.
\n" ); document.write( "sketch a left-tail of 12.10% to the left of 60
\n" ); document.write( "Find the z-value with that left tail:
\n" ); document.write( "invNorm(0.121) = -1.17
\n" ); document.write( "-----
\n" ); document.write( "sketch a right-tail of 6.3% to the right of 95
\n" ); document.write( "Find the z-value with a left tail of 93.7%
\n" ); document.write( "invNorm(0.937) = 1.53
\n" ); document.write( "--------
\n" ); document.write( "
\n" ); document.write( "I have to find µ = E[X] and σ^2 = Variance (X).
\n" ); document.write( "----
\n" ); document.write( "Form 2 equations using x = z*s + u to solve for s and u:
\n" ); document.write( "60 = -1.17*s + u
\n" ); document.write( "95 = 1.53*s + u
\n" ); document.write( "------
\n" ); document.write( "Subtract to solve for \"s\":
\n" ); document.write( "35 = 2.7s
\n" ); document.write( "s = 12.96
\n" ); document.write( "Variance = s^2 = 168
\n" ); document.write( "------
\n" ); document.write( "Solve for \"u\" using 60 = -1.17s + u
\n" ); document.write( "60 = -1.17*12.96 + u
\n" ); document.write( "u = 75.163
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
\n" ); document.write( " \n" ); document.write( "
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