document.write( "Question 260671: A lorry manufacturer in Africa claims the average annual maintanance cost for its vehicles is $500.The maintanance department of one of their customersin Kadoma Indstrial estate believes it to be higher and testss this by selecting a random sample of 6 lorries.The saple gives a mean annual maintanance cost of $555 with a standard deviation of $75.
\n" ); document.write( "Use an appropriate hypothesis test at the 5% significance level to see if the manufacturer's claim is true \n" ); document.write( "
Algebra.Com's Answer #192022 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
A lorry manufacturer in Africa claims the average annual maintanance cost for its vehicles is $500.
\n" ); document.write( "The maintanance department of one of their customersin Kadoma Industrial estate believes it to be higher and tests this by selecting a random sample of 6 lorries.
\n" ); document.write( "The sample gives a mean annual maintanance cost of $555 with a standard deviation of $75.
\n" ); document.write( "Use an appropriate hypothesis test at the 5% significance level to see if the manufacturer's claim is true
\n" ); document.write( "---
\n" ); document.write( "Ho: u = 500
\n" ); document.write( "H1: u > 500
\n" ); document.write( "----------------
\n" ); document.write( "Critical Value: invT(0.95, with df=5) = 2.0150
\n" ); document.write( "Test Stat: t(555) = (555-500)/[75/sqrt(6)] = 1.7963
\n" ); document.write( "-----
\n" ); document.write( "Conclusion: Since the TS is not in the reject interval,
\n" ); document.write( "fail to reject Ho.
\n" ); document.write( "The test results support the manufacturer's claim at the
\n" ); document.write( "5% significance level.
\n" ); document.write( "======================================================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
\n" );