In Chicago, there is a 30% chance that Memorial Day will have a high temperature in
the 70s. What is the probability that next Memorial Day will not have a high
temperature in the 70s in Chicago?
the key word is not. it says there is a 30 percent chance of it being 70. the question asks what is the percent that it is - not - 70. the equation will be 100 - 30 = 70
