odds of getting a chicken dinner

winner.js

var factArr = [1]
function fact(n) {
	if (n > factArr.length) {
		for (var i = factArr.length; i <= n; ++i) {
			factArr[i] = factArr[i - 1] * i
		}
	}
	return factArr[n]
}

function choose(n, k) {
	return fact(n) / (fact(n - k) * fact(k))
}

function binom(x, n, k) {
  return choose(n, k) * Math.pow(x, k) * Math.pow((1 - x), n - k)
}

function getSeriesWinPercent(individualWinRate, numberOfGames) {
  var sum = 0
  for(var i = Math.ceil(numberOfGames / 2); i < numberOfGames + 1; ++i) {
	sum += binom(individualWinRate, numberOfGames, i)
  }
  return sum
}

console.log(getSeriesWinPercent(.6, 5))