---
id: 5900f4a01000cf542c50ffb2
challengeType: 5
title: 'Problem 307: Chip Defects'
---
## Description
k defects are randomly distributed amongst n integrated-circuit chips produced by a factory (any number of defects may be found on a chip and each defect is independent of the other defects).
Let p(k,n) represent the probability that there is a chip with at least 3 defects.
For instance p(3,7) ≈ 0.0204081633.
Find p(20 000, 1 000 000) and give your answer rounded to 10 decimal places in the form 0.abcdefghij
## Instructions
## Tests
```yml
tests:
- text: euler307() should return 0.7311720251.
testString: 'assert.strictEqual(euler307(), 0.7311720251, ''euler307() should return 0.7311720251.'');'
```
## Challenge Seed
```js
function euler307() {
// Good luck!
return true;
}
euler307();
```