Homework Help: algebra

Posted by jenny on Wednesday, May 23, 2012 at 11:17pm.

A normal distribution has a mean of 98 and a standard deviation of 6. What is the probability that a randomly selected x-value from the distribution is at least 80?

algebra - MathMate, Thursday, May 24, 2012 at 7:57am
Normalize 80 as
(80-98)/6=-3
Look up the probability from a normal distribution table for -3 to ∞.
(It is the same value from -∞ to +3, depending on the availability of the table).
I get 0.9987.

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