A rolling stone may take two different paths. On path 1, it takes 10 seconds for it to reach the bottom of the hill, while on path 2, it takes it 15 seconds. It is twice as likely to go on path 2. How long does it take it on average? Round your answer to two decimal places.

To find the average time it takes for the rolling stone to reach the bottom of the hill, we need to consider the time it takes on each path weighted by their probabilities.

Let's assign variables:
- Time on path 1: T1 = 10 seconds
- Time on path 2: T2 = 15 seconds
- Probability of going on path 1: P1 = 1/3 (since it is twice as likely to go on path 2)
- Probability of going on path 2: P2 = 2/3

To calculate the average time, we multiply the time on each path by its respective probability and sum them up:

Average Time = (T1 * P1) + (T2 * P2)
= (10 * 1/3) + (15 * 2/3)
= (10/3) + (30/3)
= 40/3

Now we round the result to two decimal places:

Average Time ≈ 13.33 seconds

Therefore, on average, it takes the rolling stone approximately 13.33 seconds to reach the bottom of the hill.