Download Normal distribution

Warm Up
If there are 2000 students total in the school, what
percentage of the students are in each section?
50
270
680
680
270
50
Distribution Shapes
Mean & Median
Normal Distribution
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Most common distribution in statistics
Many real-life data sets follow this pattern
Examples: SAT scores, heights of people, IQ tests
Also known as a bell curve
Normal Distribution
• Mean, median and mode are all the same
• Symmetric with respect to the mean
• Highest point on the curve is the mean
Normal Distribution: COPY THIS!
.15%
2.35%
13.5%
34%
34%
13.5%
2.35%
.15%
Example 1:
Suppose that patient’s systolic blood pressures follow
a normal distribution with a mean of 108 and a
standard deviation of 14.
a) What percentage of patients have a blood pressure
of 94 or higher?
b) What percentage of patients have a blood pressure
between 80 and 122?
c) What percentage of patients have a blood
pressure of less that 80?
Example 2:
The duration of routine operations in a certain hospital
has approximately a normal distribution with an
average of 125 minutes and a standard deviation of 18
minutes.
a) What percentage of operations last 125 minutes or
more?
b) What percentage of operations lasted between 107
and 143 minutes?
c) What percentage of operations lasted between 89 and
125 minutes?
Example 3:
The mean weight of 850 college students is 70 kg and
the standard deviation of 3 kg. Assuming that the
weight is normally distributed, determine how
many students weigh:
a) Between 64 kg and 73 kg.
b) More than 76 kg.
c) Less than 67 kg.
d) Between 70 kg and 76 kg.