SOLUTION: The mean of a random variable X is E(X) = a, and the variance is D(X) = b. Find the probability P(X^2 < c). (a = -0.09, b = 1.22, c = 1.77)

Algebra ->  Probability-and-statistics -> SOLUTION: The mean of a random variable X is E(X) = a, and the variance is D(X) = b. Find the probability P(X^2 < c). (a = -0.09, b = 1.22, c = 1.77)      Log On


   



Question 1201861: The mean of a random variable X is E(X) = a, and the variance is D(X) = b. Find the probability P(X^2 < c).
(a = -0.09, b = 1.22, c = 1.77)

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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The mean of a random variable X is E(X) = a, and the variance is D(X) = b.
Find the probability P(X^2 < c).
(a = -0.09, b = 1.22, c = 1.77)
~~~~~~~~~~~~~~~~~~~


The probability  P(X^2 < c)  is the same as the probability  P( -sqrt%28c%29 < X < sqrt%28c%29 ),

which is  P = normalcdf(-sqrt%28c%29, sqrt%28c%29, a, sqrt%28b%29), if you use a regular calculator

with standard function normalcdf, standing for normal cumulative distribution function.


Using given data, you can write


    P = normalcdf(-sqrt%28c%29, sqrt%28c%29, a, sqrt%28b%29}) = normalcdf(-sqrt%281.77%29, sqrt%281.77%29, -0.09, sqrt%281.22%29) = 

      = normalcdf(-1.3304, 1.3304, -0.09, 1.1045) = 0.7701.    ANSWER

Solved.