I think this problem has two parts---
1st:- We have to calculate Instruction execution time when Instruction is in Memory.
Execution Time in this case is---
TLB hit(time to execute instruction)+TLB miss(PageTable access + time to execute instruction)
=TLB hit(time to execute instruction)+TLB miss(2*MemoryAccessTime + time to execute instruction)
=TLB hit(CPU time+2*MemoryAccessTime)+TLB miss(2*MemoryAccessTime + (CPU time+2*MemoryAccessTime))
2nd- Now we also have to include the fact that Instruction may not be in Mainmemory.Then we have to service page fault first then we execute instruction like above case
So overall effective average instruction execution time would be
=P*(PageFaultServiceTime+InstructionExceTime when in memory)+(1-P)(InstructionExceTime when in memory)
Please let me knw if there is any issue.