Question 1120396: n a recent year, a sample of grade 8 Washington State public school students taking a mathematics assessment test had a mean score of 281 with a standard deviation of 34.4. Possible test scores could range from 0 to 500. Assume that the scores are normally distributed.
Find the probability that a student had a score between 250 and 305.
Answer by amarjeeth123(570)   (Show Source):
You can put this solution on YOUR website! Mean score=µ=281
Standard deviation=σ=34.4
Score1=x1=250
Score2=x2=305
z-score z1=(x1- µ)/ σ=(250-281)/34.4=-31/34.4=-0.9011
z-score z2=(x2- µ)/ σ=(305-281)/34.4=24/34.4=0.6976
The probability for the first z-score from excel is =NORMDIST(250,281,34.4,TRUE)=0.183751
The probability for the second z-score from excel is =NORMDIST(305,281,34.4,TRUE)= 0.75731
Required probability=0.75731-0.183751=0.573559
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