#### Using the Calculator to find normal distributions.

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Using the Calculator to find normal distributions.

Using the Calculator
for Normal
Distributions
Standard Normal
Go to 2nd Distribution
Find #2 – Normalcdf
Key stroke is
Normalcdf(Begin, end)
If standardized, then mean & st. deviation do not
have to be given.
Find P(1.1<z<1.89)
Press: Normalcdf (1.1, 1.89) enter
You should get 0.1063
Check By chart method:
0.9706 – 0.8643 = 0.1063
To represent infinity we use
1E99 (1X10^99) for positive infinity
-1E99 (-1x10^99) for negative infinity
Represent in notation with ∞
Find: P(z<2.07)
Find: P(z>0.12)
Try the following
P(z < -1.23)
P(-1.2<z<2.05)
P(z>1.23)
Average age of a student is 20 with standard
deviation of 2.1 years. What’s the probability that a
student’s age is more than 23?
Finding a percentile….
Use Invnorm(%) to get the z-score
The mean score on a test is 70 with = 3. What’s the cutoff score
for the 90th percentile?
If the mean test score is 88 with standard deviation of 2, find the
cutoff scores for the middle 40%.
Homework
Worksheet