Probability of getting 2 head and 2 tail If a fair coin is tossed 4 times what is the probability that two heads and two tails will result ?
My calculation is.
no. of ways of getting exactly 2 head and 2 tails .will be $6$ out of $8$.
Eg $$HHTT,THHT,TTHH,HTTH,HTHT,THTH,HHHT,TTTH$$

There are $2^4=16$ possible outcomes:
$HHHH$ $\ \ $ $HHHT$ $\ \ $ $HHTH$ $\ \ $ $HTHH$ $\ \ $ $THHH$ $\ \ $ $\color{red}{HHTT}$ $\ \ $ $\color{red}{HTHT}$ $\ \ $ $\color{red}{THHT}$ $\ \ $ $\color{red}{HTTH}$ $\ \ $ $\color{red}{THHT}$ $\ \ $  $\color{red}{TTHH}$ $\ \ $ $HTTT$ $\ \ $ $THTT$ $\ \ $ $TTHT$ $\ \ $ $TTTH$ $\ \ $ $TTTT$ $\ \ $ 
6 of them have 2 tails and 2 heads. Thus the probability of getting 2 heads and 2 tails is 
$\frac {\text{No. of favorable outcomes}}{\text{No. of possible outcomes}}=\frac{6}{16}=\frac38$
