Distribution of results of a biased coin the mass distribution of a coin is so that the chance of getting a head s only 40% .The coin 
is tossed a 100 times
what is the chance 
-to get more than (inclusive ) 50 heads ?
-to get more than (exclusive) 50 tails?
to get more than (exclusive) 60 tails and more than (exclusive ) 20 heads ?
if you do the experiment 3times,what is the chance of getting every time less than (inclusive ) 30 heads ?

To get you started, I will work the first one.
Using the Binomial Distribution, we get
$$
\sum_{k=50}^{100}\binom{100}{k}\;.4^k\;.6^{100-k} = 0.027099197757009005051
$$
If we approximate, using the Normal Distribution, where the mean is $-.2\times100=-20$ and the variance is $.96\times100=96$, the probability of getting at least $0$ ($20/\sqrt{96}$ s.d. above the mean) is $\frac{1}{2}(1-\operatorname{erf}(20/\sqrt{96}/\sqrt{2}))=0.020613416668581847098$.
As Brian Scott points out in the comments, we can get a better approximation with the Normal Distribution by including the whole count around $50$ rather than only half the count.  That is, the probability of $49.5$ heads or more. $49.5\text{ heads}-50.5\text{ tails}=-1$ instead of $0$, which gives $19/\sqrt{96}$ or more s.d. above the mean, with a probability of $\frac{1}{2}(1-\operatorname{erf}(19/\sqrt{96}/\sqrt{2}))=0.026239749779623305681$.
