Question

A random sample of people was classified as given below.

	Prominent wrinkles	Wrinkles not prominent
Heavy smoker	130	65
Light or nonsmoker	55	250

Part 1 of 3

What is your first step before you consider finding any probabilities about this sample? If one person is selected from this sample, what is the probability the person is a heavy smoker without prominent wrinkles? Does this event of a heavy smoker without prominent wrinkles illustrate "union" or "intersection" of two events?

Answer 1

The first step is two add the entries row wise and column wise.

And find out total number of people choosen.

From the table we have total number of people is 130+65+55+250=500

Also 65 heavy smokers are without prominent wrinkles.

Hence the required probability is

The event illustrates the intersection of two events

i) people who are Heavy smokers and

ii) People Without prominent wrinkles