SOLUTION: Please answer this question for me. A random sample of 100 students who took a statistics exam were asked their score on the exam. The mean score on the test was 50; the standa

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Question 117731: Please answer this question for me.
A random sample of 100 students who took a statistics exam were asked their score on the exam. The mean score on the test was 50; the standard deviation was 10. The scores are normally distributed.
A) What percent of the students scored below 30?

B) What percent scored between 30 and 55?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A random sample of 100 students who took a statistics exam were asked their score on the exam. The mean score on the test was 50; the standard deviation was 10. The scores are normally distributed.
A) What percent of the students scored below 30?
Find the z-score for 30:
z(30)=(30-50)/10 = -2
Find P(z<-2) on your z-chart
or use normalcdf(-10,-2) = 0.0228 on your
TI calculator.
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B) What percent scored between 30 and 55?
Find the z=score for 55:
z(55)=(55-50)/10 = 1/2
Find P(-2 or use normalcdf(-2,0.5)= 0.6687
no your TI calculator.
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Cheers,
Stan H.