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Environmental Engineer

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AVG. SALARY

$90,720

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EDUCATION

Bachelor's degree

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JOB OUTLOOK

Stable

Real-Life Activities

Real-Life Math -- Solution

You are an environmental engineer working on air pollution problems.

Diesel car engines account for 3 times more pollution than the railroad. But diesel car engines emit 20 percent less than gasoline motors. What percentage of nitrous oxide emissions come from each category: gas motors, diesel engines and railroads?

Railway = r
Diesel = 3r (or 3 times the amount of railway)
Gasoline = 3r + 20 (or diesel plus 20 percent)
100 = total percentage of emissions

So, the equation for the entire emissions is:

100 = r + (3r) + (3r + 20)

Railway:

100 = r + (3r) + (3r + 20)
100 = 7r + 20
80 = 7r
80 / 7 = r
11.4 = r

Railway emissions account for 11.4 percent of total emissions.

Diesel engines:

Diesel = 3r (or 3 times the amount of railway)
Diesel = 3 (11.4)
Diesel = 34.2

Diesel engines account for 34.2 percent of total emissions.

Gasoline motors:

Gasoline = diesel + 20
Gasoline = 34.2 + 20
Gasoline = 54.2

Gasoline engines account for 54.2 percent of the nitrous oxides in the air.