The population of cirque city was 46,229 in 1999 and was 55,680 in 2010. if the population was growing exponentially, what will the population be in2020?

Start by subtracting 46,229 from 55,680 = 9,451 total growth.  

Presuming the growth is a constant of the average: divide 9,451 / 11 = 859.18 growth per year.  (2010 - 1999 = 11 years)

859.18 x 10 = 8,591 total growth 2020 - 2010 = 10 years 

Population in 2010 = 55,680 + 8,591 = 64,271 total population in 2020

Exponentially just means quickly.

Rounding decimals is very similar to rounding other numbers. if the hundredths and thousandths places of a decimal is forty-nine or less, they are dropped and the tenths place does not change. for example, rounding 0.843 to the nearest tenth would give 0.8. , your welcome !