A certain biogas consists of 75 percent methane (CH4) and 25 percent carbon dioxide (CO2) by volume.

Question:

A certain biogas consists of 75 percent methane (CH4) and 25 percent carbon dioxide (CO2) by volume. If the higher heating value of methane is 55,200kJ/kg, the higher heating value of this biogas is
(a) 25,100kJ/kg
(b) 28,800kJ/kg
(c) 33,900kJ/kg
(d) 41,400kJ/kg
(e) 55,200kJ/kg