Probability that question will solved means at least one student should be able to solve the question.
Required probability = 1/3 x 1/4 x 1/5 + 1/3 x 1/4 x 4/5 + 1/3 x 3/4 x 1/5+ 2/3 x 1/4 x1/5 + 2/3 x 3/4 x 1/5 + 2/3 x 1/4 x 4/5 + 1/3 x 3/4 x 4/5
= (1+4+3+2+6+8+12)/60
= 36/60
= 3/5 = 0.6