The probability of not drawn a red ball is 3/6. The probability of not drawn a green ball is 4/6, and the probability of not drawn a yellow ball is 5/6. So, the probability of not drawn at least one color is the multiplication of the probabilities of each color, so (3/6)*(5/6)*(4/6) = 0.2777.
For this case, the first thing we must do is define variables. We have then: x: number of minutes y: final temperature We write then the equation that models the problem: For y = 20 we have: Clearing x: Answer: The temperature of the water will be 20 degree celcius after 150 minutes