SOLUTION: This is from a practice assignment and I cannot figure out how to solve the question. I would appreciate an explanation as to how the answer is obtained rather than just the answe

Question 572725: This is from a practice assignment and I cannot figure out how to solve the question. I would appreciate an explanation as to how the answer is obtained rather than just the answer.
A math professor notices that scores from a recent exam are normally distributed with a mean of 64 and a standard deviation of 5. Answer the following questions using integer values. What score do 75% of the students exam scores fall below?
And, the professor decides to grade on a curve. If he wants .15% of the students to get an A, what is the minimum score required.
I have tried a "calculator" I found online and the answers it provided gave me 50% credit and I don't know which answer is correct as I don't know how to do the actual calculation. First answer - 67.3587. Second answer - 58.8284.
I would appreciate referral to any valid resources as it has been many, many years since I took a math class.
Thank you.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A math professor notices that scores from a recent exam are normally distributed with a mean of 64 and a standard deviation of 5. Answer the following questions using integer values. What score do 75% of the students exam scores fall below?
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Find the z-value with a left tail of 75%.
Using a TI-84 I get invNorm(0.75) = 0.6745
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Using x = zs+u solve for "x"
x = 0.6745*5+64 = 67 when rounded down
===============================================
And, the professor decides to grade on a curve. If he wants 15%
of the students to get an A, what is the minimum score required.
---
Find the z-value with a left tail of 0.85
invNorm(0.85) = 1.0364
x = 1.0364*5+64 = 69 when rounded down
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Cheers,
Stan H.
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