Probability of an event occurring at least once over n trials

helpmeplzzz

There is a 1 in 4 chance that on any given sexual encounter, Joe will contract an STD. If Joe has sex 4 times, what are the chances of him having an STD?

pwsnafu

Hint: what is the probability of not contracting after 4 times?

helpmeplzzz

1-(.75*.75*.75*.75) = my answer?

HallsofIvy

Looks good.

helpmeplzzz

So how would you do it for the probability of Joe contracting an STD twice out of those 4 occasions?

I think you would have to do a combination for this?

Mark44

As this is misplaced homework-type question, I am locking it. This thread was also posted in the Precalc section under Homework & Coursework.

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helpmeplzzz	Probability of an event occurring at least once over n trials Tweet There is a 1 in 4 chance that on any given sexual encounter, Joe will contract an STD. If Joe has sex 4 times, what are the chances of him having an STD?

pwsnafu	Hint: what is the probability of not contracting after 4 times?

HallsofIvy Recognitions: Gold Member Science Advisor Staff Emeritus	Probability of an event occurring at least once over n trials Looks good.

Mark44 Mentor	As this is misplaced homework-type question, I am locking it. This thread was also posted in the Precalc section under Homework & Coursework.