Replacement and Without Replacement
Bob and Laquisha have volunteered to serve on the Junior PromCommittee. The names of twenty volunteers, including Bob and Laquisha, are put into a bowl. If two names are randomly drawn fromthe bowl without replacement, what is the probability that Bob’s name will be drawn first and Laquisha’s name will be drawn second?
Let Bob = 1
Let Laquisha = 1
There are 20 volunteers.
I then decided to multiply (1/20) (1/20).
However, the correct answer is (1/20) (1/19)
Where did 19 comes from?
Also, what is the difference between replacement and without replacement probability questions?
Is there a simple formula for the two?