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dud
02-11-2011, 04:10 PM
Using the normal curve table for this problem. If a person received a test score that was in the top 20% of everyone who has taken the test and the test scores are normally distributed. This person's Z score must be at least:

1.46
.84
1.26
.56

tkhunny
02-11-2011, 10:40 PM
What's your emperical rule? One standard deviation is 34%-ish. Z = 1, then, would represent about 84%. That's too big. This discards two of the choices. What say you of the other two?