A country has natural gas reserves of 250 billion cubic feet. If the gas is consumed
at the rate of
3+0.02t billion cubic feet per year (where
t = 0 corresponds to now,
and t is measured in years), how long will it be before the reserves are depleted?
Round off your answer to four significant digits

Question

A country has natural gas reserves of 250 billion cubic feet. If the gas is consumed 
at the rate of 
3+0.02t billion cubic feet per year (where 
t = 0 corresponds to now, 
and t is measured in years), how long will it be before the reserves are depleted? 
Round off your answer to four significant digits

anonymous · Answer

3+.002t=250. Right? Basically I'm setting an equation where the rate the gas is consumed equals how much gas we have. This way, I can find out when all the gas is consumed, what the answer is. 
.002t=247
t=247/.002
t=123500
but since I only had 3 digits in my division we round it off to three sig figs. 
124000 years

anonymous · Answer

this is an integral question and the answer happen to be 67.94 years :/

anonymous · Answer

its 0.02 not 0.002

anonymous · Answer

Oh shoot. My bad man. Totally didn't notice that. Also my 0 key is weird so it sometimes adds extra 0s. 
In that case we have

$$\sum_{t=0}^{n}3+.02t=250$$ where n is the number of years necessary for the function to add up to 250.