Correct Answer - Option 4 : 5.4

__Concept:__

The compression ratio in otto cycle can be given as,

**\({\bf{r}} = \frac{{{V_c} + {V_s}}}{{{V_c}}}\)**

where, r = compression ratio, V_{c} = Clearance volume, V_{s} = Swept volume

__Calculation:__

__Given:__

D = 17 cm, L = 30 cm, n = Number of cylinder = 6, V_{c} = 9225 cm^{2 }

\({V_s} = \frac{\pi }{4}{D^2} \times L \times n = \frac{\pi }{4}\times{17^2} \times 30 \times 6 = 40856.41\;c{m^2}\)

\({\rm{r}} = \frac{{{V_c} + {V_s}}}{{{V_c}}} = \frac{{9225 + 40856.41}}{{9225}} = 5.42\)

**∴ The compression ratio is 5.41.**