Question 933271: a college entrance exam has a mean of 1200 and a standard deviation of 100. They will only accept applicants in the 90% percentile or higher. What is the lowest score they would need on the entrance exam?
Please help! I think I have the answer and want to check my work.
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website! Using a TI-84, I get
invNorm(0.90) = 1.28155
So z = 1.28155, and we'll use this to find the raw score x
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z = (x-mu)/sigma
1.28155 = (x-1200)/100
1.28155*100 = x-1200
128.155 = x-1200
128.155+1200 = x
1,328.155 = x
x = 1,328.155
Round up to the nearest whole number to ensure you clear the hurdle. So you need to score a 1329 or higher to be in the 90th percentile or higher.
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