A bin contains yellow and black balls. A ball is selected at random and then placed back in the bin. The results are recorded after 10 trials, 50 trials, and 150 trials. The results are recorded in the table. Based on the table, how many times can you expect that a yellow ball will be selected in 300 tries?

Outcome Number of trials: 10 50 150

Yellow: 9 32 135

Black: 1 18 15

First and third results are coherent. They both represent a probability of 0.9. Because 9 out of 10 is 9/10 = 0.9, and 135 out of 150 = 135 / 150 = 0.9. Nevertheless, second result is not coherent because 32 out of 50 is 32/50 = 0.64. I think this number must be discarded, and use 0.9 as the experimental probaility. That means that for 300 trials you should obtain x / 300 = 0.9 = > x = 0.9 * 300 = 270. Then, the answer is that you can expect that a yellow ball will be selected 270 times out of 300.