santaclara
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IN STANDARD DEVIATION, ON PAGE 20 there is Q related to TEST A AND B?
AS PER ANSWER, STUDENT DID WELL ON TEST A B/C OF 3S DEVIATION, BUT I DIDN'T UNDERSTAND THAT WHY 3S DEVIATION IS BETTER THAN 2S DEVIATION.
I WOULD REALLY APPRECIATE IF SOME ONE EXPLAIN ME THIS DEVIATION STUFF.
THANX.
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| rida
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Well let me give you an example. Basically standard deviation is how far are the numbers from the mean, how deviated are they. The reason 3S is better than 2S is because think of it this way, lets say mean is 50 for a test and standard deviation is 10. Now if someone would get a 60 on this test, that means they did one standard deviation better than the avg score of the class, if they get a 70, even better, thats 2 standard deviation above the average, and 3 would be even more better. Hence 3S on test A is better because its closer to a high score of the class according to the set standards than 2 standard deviation. Hope this helps!!
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| santaclara
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hey rida i think they didn't mention any high score through which we have to compare.
can we explain like that we add mean(30) and standard deviation(5) and is =to 35 and the again add 5 and 5 =45,so this means 3 deviation.
and for B the mean is 40 and we add 10 and then10 so we get that score i-e 60, and deviations in this 2.
may be i m wrong but i understand your example and if u have another example to explain pls explain me.
thanx rida by the way.when r u planning to go for exam?
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| rida
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Yea santaclara your rite, in the context of your question, which i had to recheck in the kaplan book, its again because Test A is 3sd and B is 2, so go with the high standard deviation as the best score, just like you said. My example was just in general how standard deviation is used, if i come across anymore examples, will definetely post them here. Hope could help, and I plan to take my exam end of june how about yourself?
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| santaclara
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Topics: 67
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thanx rida.
i hope in july or aug.
good luck for exam and keep in touch. 
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