For pipeline X
Speedup gain = Time taken for 1 instruction in Non pipeline configuration / Time taken for 1 instruction in Pipeline configuration
= (2+ 6+ 5 + 8 + 1) ns / (( 1+ 0.2 x 4) x8 )ns
=1.527
For pipeline Y
Speedup gain = Time taken for 1 instruction in Non pipeline configuration / Time taken for 1 instruction in Pipeline configuration
= (2+ 6+ 5 + 8 + 1) ns / (( 1+ 0.2 x 8) x5)ns
=1.69
Ratio Speedup of X to speedup of Y is = 1.527 / 1.69
=0.90