minwoswoh wrote:
Hi Bunuel,
One more comment...
I think that even if the question were to tell us that are indeed more than 1 green chip, the answer will still be E.
Example 1: 8 red chips and 2 green chips
Probability of both green = 2/8 * 1/7 = 1/28
Example 2: 12 red chips and 3 green chips
Probability of both green = 3/12 * 2/11 = 1/22
Example 3: 16 red chips and 4 green chips
Probability of both green = 4/16 * 3/15 = 1/20
Can we then conclude that the more quantity overall, the more chances you have of getting a green chip?
It should be:
Example 1: 8 red chips and 2 green chipsProbability of both green = 2/10 * 1/9 = 1/45
Example 2: 12 red chips and 3 green chipsProbability of both green = 3/15 * 2/14 = 1/35
Example 3: 16 red chips and 4 green chipsProbability of both green = 4/20* 3/19 = 3/95
The probability of choosing 1 green chip if the ratio of red to green is 4:1 will be the same (1/5) no matter how many total chips we have.
The probability of choosing 2 green chips will increase by increasing the total number of chips.
Hope it's clear.
It´s crystal clear now, Bunuel. This was very helpful for me to understand how DS tests the concept of Ratios vs. Concrete Numbers in Probability (since obviously, probability is expressed as a ratio itself...)