How do I solve this question, and what is the result?

Question

In 2019, in the city of Springfield (population: 198,440), approximately 226,221.6 kg/day of solid waste (approximately 82,570 tons/year) was produced.

If we consider that in 2020 Springfield had approximately 201,635 inhabitants and that with the hypothetical implementation of the project the rate of garbage per person per day would be reduced by 21%, what is the approximate generation of solid waste, in tons in Springfield during the year 2020?

Note: Consider that there was no variation in the production of solid waste per person per day between 2019 and 2020.

A. 77.130 tons/year

B. 66,237 tons/year

C. 100,090 tons/year

D. 83,900 tons/year

E. 68,200 tons/year

Thank you!

Answer 1

First we need to convert the 82,570 tons/year into tons/person•day:

82570 tons/year ÷ 198,440 = .4160955 tons/person•year

.4160955 tons/person•year ÷ 365 days = .0011399 tons/person•day

Next we reduce this amount by 21%:

.0011399( 1-.21) = .0009006 tons/person•day

Then we convert the units back into tons/year:

.0009006(201635)(365) = 66281 tons/year which is closest to B. 66,237 tons/year