SOLUTION: A variable is normally distributed with mean 21 and standard deviation 9. Use your graphing calculator to find each of the following areas. Write your answers in decimal form. Roun

Question 1155444: A variable is normally distributed with mean 21 and standard deviation 9. Use your graphing calculator to find each of the following areas. Write your answers in decimal form. Round to the nearest thousandth as needed.
a) Find the area to the left of 21.
b) Find the area to the left of 19.
c) Find the area to the right of 20.
d) Find the area to the right of 23.
e) Find the area between 19 and 26.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
area to the left of 21 is 1/2, since that is the mean
z=(x-mean)/sd
=(19-21)/9 or -2/9.The area left of z=-2/9 is 0.412
to the right of 20 is area to the right of z=-1/9 or 0.544
to the right of 23 is the area to the right of z=2/9 or 0.412, the same as the area to the left of 19.
Between 19 and 26 is the area between z=-(2/9) and z=(5/9) or 0.2987 or 0.299
from the z-values, one can go to 2ndVARS 2 (normalcdf) and put in the left sided z-value and then the right sided z-value, separated by a comma, then ENTER
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