document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=482293>Question 482293</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If anyone can help me with these questions I would greatly appreciate it as I am having problems with them &showing my work for them. Thank you.\r<BR>\n" );
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document.write( "1.	Find the critical value zc necessary to form a confidence interval at the given level of confidence. (References: definition for level of confidence  page 311, end of section exercises  5 – 8 page 317) (2.5 points each)\r<BR>\n" );
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document.write( "a.	90%       \r<BR>\n" );
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document.write( "b.	80%\r<BR>\n" );
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document.write( "2.	The new Twinkle bulb has a standard deviation of 35 hours. A random sample of 50 light bulbs is selected from inventory. The sample mean was found to be 550 hours. \r<BR>\n" );
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document.write( "a.	What is the margin of error [E] for a 90% confidence interval? Round your answer to the nearest hundredths (5 points)<BR>\n" );
document.write( "(References:  definition of margin of error on page 312 and example 2 on page 312).\r<BR>\n" );
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document.write( "b.	Construct a 90% confidence interval for the mean life of all Twinkle bulbs.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #330201 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=330201\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 1. Find the critical value zc necessary to form a confidence interval at the given level of confidence. (References: definition for level of confidence page 311, end of section exercises 5 – 8 page 317) (2.5 points each) <BR>\n" );
document.write( "a. 90%<BR>\n" );
document.write( "Find the z-value with a right tail of 5%:<BR>\n" );
document.write( "Ans: z = 1.645<BR>\n" );
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document.write( "b. 80%<BR>\n" );
document.write( "Find the z-value with a right tail of 10%:<BR>\n" );
document.write( "Ans: 1.2816<BR>\n" );
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document.write( "2. The new Twinkle bulb has a standard deviation of 35 hours. A random sample of 50 light bulbs is selected from inventory. The sample mean was found to be<BR>\n" );
document.write( "550 hours.<BR>\n" );
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document.write( "a. What is the margin of error [E] for a 90% confidence interval? Round your answer to the nearest hundredths (5 points)<BR>\n" );
document.write( "ME = 1.645 = 8.14\r<BR>\n" );
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document.write( "(References: definition of margin of error on page 312 and example 2 on page 312). \r<BR>\n" );
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document.write( "b. Construct a 90% confidence interval for the mean life of all Twinkle bulbs. <BR>\n" );
document.write( "x-bar = 550<BR>\n" );
document.write( "ME = 1.9126<BR>\n" );
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document.write( "90% CI: 550-8.14 < u < 550+8.14<BR>\n" );
document.write( "541.86 < u < 558.14<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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