SOLUTION: Mean score of an statistic exam is 75 and normally distributed. The probability between 55 and 60 is 4.41% and the probability of students scoring more, 90 is 6.61%. What is the p

Algebra ->  Probability-and-statistics -> SOLUTION: Mean score of an statistic exam is 75 and normally distributed. The probability between 55 and 60 is 4.41% and the probability of students scoring more, 90 is 6.61%. What is the p      Log On


   

Question 1083079: Mean score of an statistic exam is 75 and normally distributed. The probability between 55 and 60 is 4.41% and the probability of students scoring more, 90 is 6.61%.
What is the probability of students scoring between 60 and 95 ?
Answer by mathmate(429) About Me  (Show Source):
You can put this solution on YOUR website!
For this particular problem, it can be solved quickly, as follows:
P%2860%3CX%3C95+%29
=P%28X%3C95%29-P%28X%3C60%29
=P%28X%3E55%29-P%28X%3E90%29 ..... recall that mean=75, and normal distr. is symm about mean
=P%2855%3CX%3C60%29%2BP%28X%3E60%29-0.0661
=0.0441%2B%281-P%28X%3E90%29%29-0.0661
=0.0441%2B%281-0.0661%29-0.0661
=0.9119

A more general way is to solve for the standard deviation, and solve accordingly. Standard deviation will be found to be 9.9639.