- #1

maiad

- 102

- 0

**Finding probabilities through general addition rule**

## Homework Statement

http://postimg.org/image/q9ztktpot/ [Broken]

## Homework Equations

P(A or B)=P(A)+P(B)-P(A and B)

P(A and B)=P(A)P(B)

## The Attempt at a Solution

The question is for part b). It said it was only focused on the mens so i ignored all the other numbers.

I used the general addition rule where P(A or B)=P(A)+P(B)-P(A and B). Since these events are independent, i used this equation... P(A and B)=P(A)P(B). I found P(A) from 400/2000= 0.2

I found P(B) from 500/2000=0.25. Then i found P(A and B)=P(A)P(B)=0.05

Now i plugged it into the general addition rule... P(A or B)=0.2+0.25-0.05=0.4 but it was wrong.

What did i do wrong?

Last edited by a moderator: