I am getting answer as 88.6 time unit.
using Total page service time = 250 x 0.94 + 0.06 x 450 = 262 time units
Access time = p( page service time + m) + (1-p)(m) = p * page service time + m ( p is page fault rate)
Substituting the values i got access time = 88.6 time unit.
but the answer is 85.6 time unit. Please point where i am going wrong.