Gaming World Forums
General Category => General Talk => Topic started by: something bizarre and impractical on January 29, 2009, 06:06:05 am
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Ok, this isn't for me but I'm trying to help my friend and I have no background in statistics except what I've read here and there. Tell me if this is correct.
A particular automatic sprinkler system for high-rise apartment buildings, office buildings, and hotels has two different types of activation devices for each sprinkler head. One type has a reliability of .91 (i.e., the probability that it will activate the sprinkler when it should is .91). the other type, which operates independently of the first time, has a reliability of .87. Suppose a serious fire starts near a particular sprinkler head.
a. What is the probability that any sprinkler head will be activated?
b. What is the probability that both of the sprinkler heads with be activated?
I think that the answers are:
a. (1 - (1-0.87)(1-0.91)) = 98.83% chance one of them are activated
b. (0.87)(0.91) = 79.17% chance both of them are activated
edited because I made some obvious errors!!