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Old 2003-12-13, 02:41   #2
wblipp's Avatar
May 2003
New Haven

234010 Posts

There is a simple and well known formula for the variance of binomial distribution - you should probably look it up and memorize it for the exam. If you must derive it, then find the variance of the outcome for flipping the coin one time, then note that 1800 flips is the sum of 1800 iid random variable, so their variances add.
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