document.write( "Question 1197734: The financial aid officer at a South African university wishes to estimate the mean cost of textbooks per semester for students. For the estimate to be useful it should be within R{13} of the true population mean. How large a sample should be used in order to be 95% confident of achieving this level of accuracy if we know the population standard deviation is R{92}? \n" ); document.write( "

Algebra.Com's Answer #831445 by ewatrrr(24785) $\"\"$ $\"About$

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$\"z+=blue+%28x+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29\"$
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\n" ); document.write( "Me = 13, 92 and z = 1.96 ( 95% confidence interval)
\n" ); document.write( " n = $\"+%28z%2Ablue%28sigma%29%2FME%29%5E2\"$ = $\"+%281.96%2Ablue%2892%29%2F13%29%5E2\"$ = 192.4
\n" ); document.write( "n = 193 (always round up for sample size)\r
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