probability of coin toss, please help :)

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probability of coin toss, please help :)

Post by Fa23 » Thu Jan 20, 2011 9:15 pm

if 2 coins are tossed 20 times, how many of those tosses would you expect to result in both coins landing heads up? show your calculations.

my attempt:

for each toss the probability of heads is 0.5
therefore the probability of heads for both coins is 0.5 * 0.5 = 0.25

5/20 times the coins will both be heads up.

is this all correct? any help would be appreciated. thanks

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Inland Taipan
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Post by JackBean » Fri Jan 21, 2011 8:27 am

seems fine to me

why are there so many math questions now? :roll:

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Post by Rap » Sun Jan 23, 2011 6:50 pm

5 is the average number of times two heads will turn up. It is possible for anything from zero to 20 to happen though.

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