document.write( "Question 686885: I made 20 measurements of friction on one type of material with average result of friction 30,5 % and another 20 measurement of friction on second type of material with average result of 35,5 %. Now I would like to know, whether this difference is significant, using alpha 0,05. Please, could you help?
\n" ); document.write( "Many thanks. \n" ); document.write( "

Algebra.Com's Answer #424996 by stanbon(75887) $\"\"$ $\"About$

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I made 20 measurements of friction on one type of material with average result of friction 30,5 % and another 20 measurement of friction on second type of material with average result of 35,5 %. Now I would like to know, whether this difference is significant, using alpha 0,05. Please, could you help?
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\n" ); document.write( "Ho: p1-p2 = 0
\n" ); document.write( "Ha: p1-p2 # 0
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\n" ); document.write( "test statistic:
\n" ); document.write( "z = (0.305-0.355)/sqrt[(0.305*0.695/20) + (0.355*0.645/20)]
\n" ); document.write( "= -0.05/0.1485
\n" ); document.write( "= -0.3367
\n" ); document.write( "-----
\n" ); document.write( "Critical values for 2-tail test with alpha = 5%: +-1.96
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\n" ); document.write( "Conclusion: Since the test stat is not in the reject interval,
\n" ); document.write( "fail to reject Ho.
\n" ); document.write( "There is no significant difference at the 5% level.
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

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