2.3 Energy expenditure in walking (🕒✎)

A medium-sized apple contains about 95 Cal (note that 1 Cal = 1 kcal ≈ 4184 J). Assuming 60% efficiency in conversion of an apple to available energy, how far can a person weighing 70 kg walk using all of the apple’s energy while maintaining a comfortable pace with Froude number = 0.25? Assume a leg length of 0.9 m.