The number of aluminum cans used each year varies directly as the number of people using the cans. if 500 people use 120000 cans in one year, how many cans are used each year in a city which has a population of 130000?

Answer

31,200,000

Explanation

Firstly, calculate the constant of proportionality.

Al ∝ N

Al = kN     Where Al = number of aluminium cans, k = constant and N = number of people using the can.

Al = kN

k = Al/N

  = 120000/500

  = 240

Equation becomes;

Al = 240N

For 130000 cans;

Al = 240 × 130000

   = 31,200,000

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