Question 888631
Z score for someone with 340 :
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{{{(340-300)/20 = 2}}} 
It is simply how many units of "20" the persion deviates from the mean "300". The person who scores 340 deviates two standard deviations of "20" from the mean.
Answer: 2.
If we have 310, the same logic applies: {{{(310-300)/20 = 0.5}}} 
260: {{{(260-300)/20 = -2}}} 
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With Z-scores, it's how many standard deviations away from the mean you are.
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Z-score 2.4:
Take the mean and add 2.4 times the standard deviation.
300+2.4*20 = 348.
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For the two others:
300+1.5*20 = 330
300-4.5*20 = 210
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Hope that helps. :)