# If you flip a fair coin four times, what is the probability that there you get heads twice?

##### 1 Answer

Nov 1, 2015

You can attack this problem in several ways.

#### Explanation:

Since there are only 16 combinations (2 for the first, times the second, third and fourth) you can write them out:

HHHH, HHHT, HHTH, HHTT, etc.

And filter out the right ones. Divide this by

**Or:**

You can use the binomial function on your GC.

I use a TI-83 Plus:

2nd-distr -- binompdf(4, 0.5, 2)

(This means: 4 tries, chance =0.5, exactly 2 good outcomes)