An experimental probability is given by the number of observations divided by the number of trials.
From the given table it can be seen that the color with the highest frequency is red with 9 observations while that number of trials is given by the sum of the individual observations, i.e 7 + 9 + 6 + 8 = 30
Therefore, the experimental probability of the highest frequeny is given by 9 / 30 = 0.3