The total number of times the cube was rolled is 13 + 16 + 15 + 17 + 19 + 20 = 100
The experimental probability for each number rolled is given by:
P(1) = 13/100 = 13%
P(2) = 16/100 = 16%
P(3) = 15/100 = 15%
P(4) = 17/100 = 17%
P(5) = 19/100 = 19%
P(6) = 20/100 = 20%
Therefore, the probability of rolling at least 3 is given by:
P(>=3) = P(3) + P(4) + P(5) + P(6) = 15% + 17% + 19% + 20% = 71%