For households: (1,500,000/5 * 2) + (5,000,000/5 * 5) + (2,000,000/5 * 8) = 8,800,000 tube lights

For office complexes: ((500+100+50)*20) + ((50+10+5)*40) + ((10+5)*80) = 16,800 tube lights

So, total ...read more

Start with thinking where all will you find Tubelights and then estimate basis area calculations, hotspots, density, need for tubelights. This is a typical Guesstimate question.