$2.$ A processor executes an instruction in the following six stages. The time required by each stage in picoseconds is given for each stage.

IF Instruction fetch $300$ ps

ID Instruction decode $150$ ps

OF Operand fetch $250$ ps

OE Execute $350$ ps

M Memory access $700$ ps

OS Operand store $($writeback$)200$ ps Once the pipeline is full, what is the average instruction rate?