Source : https://www.hackerrank.com/challenges/s10-mcq-3
Objective
In this challenge, we practice calculating the probability of a compound event. We recommend you review today's Probability Tutorial before attempting this challenge.
Task
There are urns labeled , , and .
- Urn contains red balls and black balls.
- Urn contains red balls and black balls.
- Urn contains red balls and black balls.
One ball is drawn from each of the urns. What is the probability that, of the balls drawn, are red and is black?
Source : https://www.hackerrank.com/challenges/s10-mcq-3
Solution
| github.com/RodneyShag | |
| Answer: 17/42 | |
| Urn X has a 4/7 probability of giving a red ball | |
| Urn Y has a 5/9 probability of giving a red ball | |
| Urn Z has a 1/2 probability of giving a red ball | |
| Urn X has a 3/7 probability of giving a black ball | |
| Urn Y has a 4/9 probability of giving a black ball | |
| Urn Z has a 1/2 probability of giving a black ball | |
| P(2 red, 1 black) = P(Red Red Black) + P(Red Black Red) + P(Black Red Red) | |
| = (4/7)(5/9)(1/2) + (4/7)(4/9)(1/2) + (3/7)(5/9)(1/2) | |
| = 20/126 + 16/126 + 15/126 | |
| = 51/126 | |
| = 17/42 |
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