The number 8 has factors 1, 2, 4 and 8.
The only numbers in the spin greater than 6 are 7 and 8,
The probability that the student will spin a factor of 8 three times in a row is given by: (4/8)*(4/8)*(4/8) = (1/2)*(1/2)*(1/2) = 1/8
The probability that the student will spin a number greater than 6 three times in a row is given by (2/8)*(2/8)*(2/8) = (1/4)*(1/4)*(1/4) = 1/64
Then, the difference between these two probabilities is given by 1/8 - 1/64 = 7/64