Did I solve this correct is my answer correct

What is the speedup of the basic pipeline (without bypassing) shown in the Introduction
slides (Tsequential / Tpipelined) if 1/5 of all instructions contain a data dependence? Can you
give a general formula for a k-stage pipeline? What other information do you need to know?
100 * 1 = 100 cycles
500 cycle
Tpipelined = 108 cycles
(100 * 1) = 100
4 * 2 (because of stall) = 8
Tpipelined=100+8=108 cycles
General Formula: Speedup = Tsequential / Tpipelined
500 / 108 ≈ 4.63

If I am wrong please explain to me