A commercial deep-sea mining operation estimates its annual extraction of rare earth minerals as follows:
Model P P\,P assumes that the mass of minerals extracted will increase by the same amount each year.
Using model PPP, find the mass of minerals extracted in year 4. Give your answer to the nearest 10 tonnes.
Model Q Q\,Q assumes that the mass of minerals extracted will increase by the same percentage each year.
Using model QQQ, find the mass of minerals extracted in year 2. Give your answer to the nearest 10 tonnes.
Calculate, according to the two models, the difference between the total mass of minerals extracted from year 1 to year 8 inclusive. Give your answer to the nearest 10 tonnes.