The mean grade in Mathematics of Grade 11 students from school A is 83 with standard deviation of 4, while the mean grade in Mathematics of Grade 11 students from school B is 87 with standard deviation of 5. Using 49 samples from school A and 64 from school B, what is the probability that the mean grade of students from school B exceeds the mean grade of students from school A by at least 3 but less than 5?