document.write( "Question 610782: A random sample of 50 calls initiated on cellular car phones had a mean duration of 3.5 minutes with standard deviation 1.2 minutes. Find 99% confidence interval for the mean duration of telephone calls initiated on a cellular car phone. \n" ); document.write( "
Algebra.Com's Answer #384586 by ewatrrr(24785)\"\" \"About 
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document.write( "Hi, 
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document.write( "50 calls initiated on cellular car phones with mean duration of 3.5 minutes & SD = 1.2 minutes
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document.write( "Find 99% confidence interval for the mean duration of telephone calls initiated on a cellular car phone.
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document.write( "  ME = \"+2.576%2A1.2%2Fsqrt%2850%29\" = .437
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document.write( " CI: 3.5-.437> u < 3.5+.437
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document.write( " CI: 3.063 > u < 3.947
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document.write( "Note: -------------------------------------------------------------
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document.write( "	a	a/2	crtical regions	
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document.write( "80%	0.2	10%	z <-1.28155	z >+1.28155
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document.write( "90%	0.1	5%	z <-1.645	          z >+1.645
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document.write( "92%	0.8	4%	z <-1.751	          z >+1.751
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document.write( "95%	0.05	2.50%	z <-1.96	          z >+1.96
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document.write( "98%	0.02	1%	z <-2.33	          z >+2.33
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document.write( "99%	0.01	0.50%	z<-2.576	          z >+2.576
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