document.write( "Question 418462: Vitamin D is an essential ingredient for maintaining strong bones and teeth. Sources of this vitamin are natural sunlight and certain dietary supplements. There is a growing concern among pediatricians that today's youngsters are spending too much time indoors. This increases the risk of vitamin D deficiency and all of its related health issues. A research team would like to estimate the proportion of children (aged 6 to 12) that currently exhibit a deficiency in this micro-nutrient. For their purposes a 90% CI must be no wider than 9.5% to be useful. Given these constraints, the number of children required for the sample is? \n" ); document.write( "
Algebra.Com's Answer #292830 by stanbon(75887)\"\" \"About 
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A research team would like to estimate the proportion of children (aged 6 to 12) that currently exhibit a deficiency in this micro-nutrient.
\n" ); document.write( "For their purposes a 90% CI must be no wider than 9.5% to be useful. Given these constraints, the number of children required for the sample is?
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\n" ); document.write( "2*E = 0.095
\n" ); document.write( "E = 0.0475
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\n" ); document.write( "E = zs/sqrt(n)
\n" ); document.write( "0.0475 = 1.645*s/sqrt(n)
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\n" ); document.write( "n >= [1.645s/0.0475]^2
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\n" ); document.write( "I believe you need a value of the standard deviation (s).
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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