 
Summary: Math 140
Introductory Statistics
Professor Bernardo Ábrego
Lecture 5
Sections 2.4, 4.1
Example (p. 91)
According to the table on page 87, the death rates
per 100,000 residents from cancer are approximately
normal, with mean 196 and SD 31. The middle 90%
of death rates are between what two numbers?
Example (p. 91)
According to the table on page 87, the death rates
per 100,000 residents from cancer are approximately
normal, with mean 196 and SD 31. The middle 90%
of death rates are between what two numbers?
Unstandardize z = 1.64485 and z = 1.64485
So the middle 90 of death rates are between 145.009
and 246.99 deaths per 1000,000 residents
x = mean + z ˘ SD = x + z ˘ SDx = mean + z ˘ SD = x + z ˘ SD
x = 196 + (ˇ1:64485)(31) = 145:0096x = 196 + (ˇ1:64485)(31) = 145:0096
