In a factory, there are 3 machines working 23 hours a day. The owner decided to buy a fourth machine, which works only 12 hours a day. One machine can produce 2 kg of material every hour. The factory sells the produced material for $50 per 1 kg. How much can this factory earn in one day? Let's think first. Chain of thought:
The total runtime for the first three machines is 3 machines * 23 hours / day / machine = 69 hours / day. So these machines could produce 69 hours / day * 2 kg / hour = 138 kg / day. The fourth machine could produce 12 hours / day * 2 kg / hour = 24 kg / day of material. In total all the machines would produce 138 kg / day + 24 kg / day = 162 kg / day of material. The factory would therefore earn 162 kg / day * $50 / kg = $8100 / day.
Therefore, the answer is 8100.