Dear Anurag
I would to explain you the answer of this question
Empirical formula -
An Empirical formula represents the simplest whole number ratio of various atoms present in a compound.

General equation for combustion of hydrocarbon:

CxHy + (x+ y/4)O2 -> xCO2 + (y/2)H2O

Number of moles of CO2 produced = 3.08/44 = 0.07

Number of moles of H2O produced = 0.72/18 = 0.04

SO, x / (y/2) = 0.07/0.04 =  7/4

The formula of hydrocarbon is C7H8

I hope you understand this answer

All the best