# Probabilty Question

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• November 7th 2008, 04:51 AM
JohhnySD
Probabilty Question
p=80% (chance of winning a game)
n=5 (number of games)

What is the probability that you will win at least 4 games (find the probability that x is greater than or equal to 4).
• November 7th 2008, 05:26 AM
Soroban
Hello, JohhnySD!

This is a Binomial probability.

Quote:

p = 80% (chance of winning a game)
n = 5 (number of games)

What is the probability that you will win at least 4 games?

"Win at least 4 games" means "Win 4 games or Win 5 games."

. . $P(x\!=\!4) \;=\;{5\choose4}(0.8)^4(0.2)^1 \;=\;0.4096$

. . $P(x\!=\!5) \;=\;{5\choose5}(0.8)^5(0.2)^0 \;=\;0.32768$

Therefore: . $P(x \geq 4) \;=\;0.4096 + 0.32768 \;=\;0.73728 \;\approx\;73.7$%

• November 7th 2008, 05:43 AM
JohhnySD
thank you so much!!
• November 8th 2008, 07:41 AM
CaptainBlack
Quote:

Originally Posted by JohhnySD
thank you so much!!

Why not use the thanks button then?

CB