document.write( "Question 516991: 4. Strength tests carried out on samples of two yarns spun to the same count gave the following results: \n" );
document.write( " Number in \n" );
document.write( "sample Sample \n" );
document.write( "Mean Sample \n" );
document.write( "variance \n" );
document.write( "Yarn A 4 50 42 \n" );
document.write( "Yarn B 9 42 56\r \n" );
document.write( "\n" );
document.write( "The strengths are expressed in pounds. Does the difference in mean strengths indicate a real difference in the mean strengths of the yarn? \n" );
document.write( " \n" );
document.write( "
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