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anonymous
 one year ago
Applicants to a college psychology department have normally distributed GRE (Graduate Record Exam) scores with a mean of 544 and a standard deviation of 103. What is the GRE score at the 77th percentile? Round answer to the nearest whole number.
A. 620
B.505
C.468
D.1
E.1
not really sure how to do this problem, i did it two different ways and got two different answers and both those answers weren't a choice. Someone please help me walk through the steps if you know the answer :)
anonymous
 one year ago
Applicants to a college psychology department have normally distributed GRE (Graduate Record Exam) scores with a mean of 544 and a standard deviation of 103. What is the GRE score at the 77th percentile? Round answer to the nearest whole number. A. 620 B.505 C.468 D.1 E.1 not really sure how to do this problem, i did it two different ways and got two different answers and both those answers weren't a choice. Someone please help me walk through the steps if you know the answer :)

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phi
 one year ago
Best ResponseYou've already chosen the best response.1The first step is use a table to find how many standard deviations (above the mean) correspond to 0.77 Do you know how to do that ?

phi
 one year ago
Best ResponseYou've already chosen the best response.1As you know, the area under the bell curve from the "left tail" up to the mean is 1/2 of the total area. In other words, 0.5 of the area is below 544

phi
 one year ago
Best ResponseYou've already chosen the best response.177% or 0.77 means we want the score where 0.77 of the total area is below that score. dw:1444743374539:dw common sense says that this score must be bigger than the mean 544 so we can answer the question by process of elimination: only 1 of your choices works.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh so it would have to be 620 then?

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes. 620 If we looked in a table, we would find 0.739 standard deviations above the mean is what we want. The std dev for this problem is 103, so we want to be 103*0.739= 76.1 points above the mean. so we want a score of 544+76= 620

phi
 one year ago
Best ResponseYou've already chosen the best response.1Here is a useful tool http://davidmlane.com/hyperstat/z_table.html

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh okay thank you, yeah the first time i looked at a zscore table i got the value wrong for .77 thank you!

phi
 one year ago
Best ResponseYou've already chosen the best response.1If they want you to learn how to use a table (which may be confusing) , you should practice until it makes sense.
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