HP 48g Graphing Calculator User Manual
Page 148
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Example:
The scores on a final exam approximate a normal curve
wuth a mean of 71 and standard deviation of 11. What
percentage of the students scored between 70 and 89?
12
71
70
89
Step 1:
First, calculate the probability that a student chosen at
random obtained a score greater than 70. (Square the
standard deviation to get the variance.)
(IvrnTl fN^
7 1 (
e n t e r
!
11 QCZD
7 0 L I T F ' N
(
n x t
!
1:
.536217586697
Step 2:
Now, do the same calculation for a score of 89, after recalling
the last argument used.
8 9 U T P N
2=
.536217586697
1:
5.08817524756E-2
Step 3:
Subtract the two values. About 49% of the students scored
between 70 and 89.
0
1:
.485335834221
12-6 Functions of Real and Complex Numbers