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Lost in probability
Message posted by Melanie (via 198.208.6.35) on September 10, 2001 at 2:28 PM (ET)
Hi,
Can anyone help me with a foirmula to solve this? I'm trying to do it using a z value of .522 for the 70th percentile, but it just isn't working out.
The question is worded (to me) awkwardly. It states:
A program will only admit students with the top 30% math skills. What is the lowest math skill score they will accept? The mean is 497 and the standard deviation is 115.
READERS RESPOND:
(In chronological order. Most recent at the bottom.)
Re: Lost in probability
Message posted by Bill (via 192.231.71.10) on September 10, 2001 at 4:29 PM (ET)
z=x-x(bar)/sd. In your case you know z so that .522=x-497/115. Solve for x. Also, see http://davidmlane.com/hyperstat/z_table.html.
Re: Lost in probability
Message posted by Melanie (via 198.208.6.35) on September 10, 2001 at 4:38 PM (ET)
Thanks, but now I'm even more confused. I get 3.798. I don't get what this means.
Re: Lost in probability
Message posted by Tomi (via 154.32.143.135) on September 11, 2001 at 3:11 AM (ET)
Bill left out some crucial brackets.The equation you need to solve is:
.522=(x-497)/115
.522*115=x-497
60=x-497
557=x
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