X has a normal distribution with a mean of 80.0 and a standard deviation of 4.0
A. P(x<78.0) B. P(75.0 < x < 85.0) C. P(x > 82.0)
- Anonymous9 years agoFavorite Answer
First find the z-score.
Then look up the p-value on a z-table.
(Keep in mind that a z table finds the probability of all values below the value you specified.)
P-value on z table= .3085
[B] Do the same thing for this one also. Find the p-value for each specific value (75.0 and 85.0) but in this case you must subtract the p-value of the 85.0 from the p-value of the 75.0 to find the p-value in between the two specified values.
[C] Find p-value then subtract from 1 to find the probability of a value being over 82.0.
(P-value means the same thing as probability.)
You're welcome! (:
Hope this helps!Source(s): AP Statistics :D