If you flip a fair coin 7 times, what is the probability that you will get exactly 2 tails?
+2407 There are 2^7 ways of flipping 7 choices.
There are 7*6/2 = 21 ways of having two heads.
So I think the answer is 21/2^7 = 21/128
I hope this helped. :))
=^._.^=
+237 The probability of exactly two tails is
7C2 (1/2)^7 = 21/128
since there are 7C2 = 21 ways to choose 2 from 7, and every specific sequence of 7 throws has probability (1/2)^7.
