Homework Help: math

Posted by helpme on Saturday, November 1, 2008 at 6:13pm.

hi i did this problem and i just want to know if its right.
3 coins are flipped , find the following probabilities:
a) P(2 heads)
b) P( at most 2 heads)
c) P(no heads)

i got
a) 1/4
b) .75
c) 5/8

math - drwls, Saturday, November 1, 2008 at 7:25pm
There are 8 possible outcomes
HHH TTT
HHT TTH
HTT THH
HTH THT

a) wrong 3 out of 8 have two heads
b) wrong. "At most two" is the same as "not three heads" 7 out of 8 don't have three heads.
c) wrong again "no heads" is the same as "all tails"

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