document.write( "Question 507513: Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work.
\n" ); document.write( "Errors Frequency
\n" ); document.write( "36-38 18
\n" ); document.write( "39-41 7
\n" ); document.write( "42-44 12
\n" ); document.write( "45-47 22
\n" ); document.write( "48-50 13\r
\n" ); document.write( "\n" ); document.write( "This is what I have so far, not sure if I'm on the right track.\r
\n" ); document.write( "\n" ); document.write( "Mean: 18+7+12+22+13=72/5= 14.4\r
\n" ); document.write( "\n" ); document.write( "Standard deviation = 3.6, -7.4, -2.4, 7.6, 1.4\r
\n" ); document.write( "\n" ); document.write( "Variance = I am lost now\r
\n" ); document.write( "\n" ); document.write( "I really some guidance here, I have been working on this for awhile can't seem to get it. Any help and explanation please \n" ); document.write( "

Algebra.Com's Answer #340641 by stanbon(75887) $\"\"$ $\"About$

You can put this solution on YOUR website!
Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work.
\n" ); document.write( "Errors Frequency
\n" ); document.write( "36-38 18
\n" ); document.write( "39-41 7
\n" ); document.write( "42-44 12
\n" ); document.write( "45-47 22
\n" ); document.write( "48-50 13
\n" ); document.write( "----
\n" ); document.write( "You have to use each class mark as the representative data value
\n" ); document.write( "for each class:
\n" ); document.write( "1st class mark is (38+36)/2 = 37
\n" ); document.write( "Do the same for each class.
\n" ); document.write( "---
\n" ); document.write( "Mean = [37*18+40*7+41*12+46*22+49*13]/[18+7+12+22+13] = 43
\n" ); document.write( "std = 4.7434
\n" ); document.write( "variance = 4.7434^2 = 22.4998
\n" ); document.write( "============================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

\n" );