Help with Section 7.2 Questions #12, 13
A percentile is the data value that has a specified area found to the LEFT of the data value. We use the
I
NVNORM
to calculate a data value from a normal distribution:
INVNORM
(area to the left,mean,standard deviation)
For example, if you were asked to fin
d the 25th percentile for women’s heights (assuming heights are
normally distributed) where the mean is 62 inches and the standard deviation is 5 inches then I would
use the
INVNORM
function as follows:
INVNORM(0.25,62,5)= 58.63 inches
If I were then ask
ed to find the 50th percentile (which it the same thing as asking for the median of the
distribution):
INVNORM(0.50,62,5)=62
If I were then asked to find the 75th percentile
INVNORM(0.75,62,5)=65.37
You’ll notice the answers get larger as the area to
the left increases.
Help with Section 7.2 Questions #12, 13
A percentile is the data value that has a specified area found to the LEFT of the data value. We use the
INVNORM to calculate a data value from a normal distribution:
INVNORM(area to the left,mean,standard deviation)
For example, if you were asked to find the 25th percentile for women’s heights (assuming heights are
normally distributed) where the mean is 62 inches and the standard deviation is 5 inches then I would
use the INVNORM function as follows:
INVNORM(0.25,62,5)= 58.63 inches
If I were then asked to find the 50th percentile (which it the same thing as asking for the median of the
distribution):
INVNORM(0.50,62,5)=62
If I were then asked to find the 75th percentile
INVNORM(0.75,62,5)=65.37
You’ll notice the answers get larger as the area to the left increases.
