Then the class size is: 6 ÷ 0.12 = 50;

(2) Excellent rate of the whole class1-0.14-0.36 = 0.5 = 50%;

(3) The frequencies of the third and fourth groups are: 0. 12×9+83=0.68,

Then the sum of the frequencies of the last two groups is:1-0.14-0.68 = 0.18,

Then the probability of Xiao Ming getting an A+ is 0. 18.