SOLUTION: A continous random variable X is normlly distributed with mean U>0 and variance 2UČ.It is also known that Pr(x less than or equal to 20)=0.90 find the probability that 15 less tha

Algebra ->  Probability-and-statistics -> SOLUTION: A continous random variable X is normlly distributed with mean U>0 and variance 2UČ.It is also known that Pr(x less than or equal to 20)=0.90 find the probability that 15 less tha      Log On


   

Question 1021895: A continous random variable X is normlly distributed with mean U>0 and variance 2UČ.It is also known that Pr(x less than or equal to 20)=0.90
find the probability that 15 less than or equal to x less thn or equal to 25.
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
we are given that .
Using a standard normal table, it follows that %2820-mu%29%2F%28sqrt%282%29%2Amu%29+=+1.285.
solving for mu, we get mu+=+7.
==> mean is 7 and variance is 2mu%5E2+=+98.
==>
=P%280.808+%3C=+Z+%3C=+1.818%29
= 0.9656 - 0.7910 = highlight%280.1746%29