document.write( "Question 1197540: You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately
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\n" ); document.write( " dollars. You would like to be 98% confident that your estimate is within 2 dollar(s) of average spending on the birthday parties. How many moms do you have to sample? Do not round mid-calculation.\r
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\n" ); document.write( "\n" ); document.write( "Try this with your statistics calculator, if you increases the confidence level, the sample size
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\n" ); document.write( "\n" ); document.write( "If you increases the error bound, the sample size
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Algebra.Com's Answer #830872 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "Hi  \r\n" );
document.write( " 98% confident  ⇒  z = 2.326 (See below)\r\n" );
document.write( "σ = $21.8,   ME = 2\r\n" );
document.write( "How large of a sample size is required? \r\n" );
document.write( "ME large relative to  σ  ... Expect Sample size to be small\r\n" );
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document.write( "n = \r\n" );
document.write( "n =  = 12.7  0r sample Size = 13 (always round Up)\r\n" );
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document.write( " = CI	z = value\r\n" );
document.write( "90%	z =1.645  \r\n" );
document.write( "92%	z = 1.751\r\n" );
document.write( "95%	z = 1.96   \r\n" );
document.write( "98%	z = 2.326   Invnorm(.99)  2-sided (.98 + .02/2 = .99 ) \r\n" );
document.write( "99%	z = 2.576\r\n" );
document.write( "Wish You the Best in your Studies.\r\n" );
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