geometric progression word problem,
A liquid is kept in a barrel. At the start of a year the barrel is filled with 160 litres of the liquid. Due to evaporation, at the end of every year the amount of liquid in the barrel is reduced by 15% of its volume at the start of the year.
Liquid at the start of the year = 160
(a) Calculate the amount of liquid in the barrel at the end of the first year.
end of 1st year = 160x0.85 = 136ml
Liquid at end of year 10=160×(0.85)^10=31.499 … =31.5 litres
(b) Show that the amount of liquid in the barrel at the end of ten years is approximately 31.5 litres.
need help with part 'c'
At the start of each year a new barrel is filled with 160 litres of liquid so that, at the end of 20 years, there are 20 barrels containing liquid.
(c) Calculate the total amount of liquid, to the nearest litre, in the barrels at the end of 20 years.