# What is the variance of 10 coin flips?

Nov 2, 2015

Assuming that the coins are unbiased, the answer is 2.5.

#### Explanation:

Flipping coins comes under the binomial distribution. For a binomial distribution, the parameters are n, p, and q. The variance is then given by npq.

Here, 10 coins are flipped. so n = 10
the coin is unbiased - so p = $\left(\frac{1}{2}\right)$
q = 1 - p = 1 - $\left(\frac{1}{2}\right)$ = $\left(\frac{1}{2}\right)$
variance is 10 $\left(\frac{1}{2}\right)$ $\left(\frac{1}{2}\right)$ = 2.5