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maiad
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Finding probabilities through general addition rule
http://postimg.org/image/q9ztktpot/
P(A or B)=P(A)+P(B)-P(A and B)
P(A and B)=P(A)P(B)
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?
Homework Statement
http://postimg.org/image/q9ztktpot/
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?
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