The amount W of water used varies directly with the population 'N' of people. City 'A' has a population of 483,000 people and used 37.6 billion gallons of water in a fiscal year. Find out how many billion gallons of water we would expect City 'B' to use if we know that its population is 150,000

W= (?) Billion of gallons of water
Type an integer or decimal rounded to the nearest tenth as needed.

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sedji sedji · Answer 1 · 2017-12-03T04:50:18+01:00

Set it up as a proportion.
483000/37.6=150000/x
Cross multiply
483000x=5640000
X=11.677
X=11.68

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MrRoyal MrRoyal · Answer 2 · 2022-03-15T12:16:41+01:00

The amount of water used by a population of 150000 is 11.7 billion

The variation is a direct variation.

So, we have:

[tex]W \alpha N[/tex]

Express as equation

[tex]W = kN[/tex]

Where k represents the constant of variation.

Make k the subject

[tex]k = \frac WN[/tex]

The equation becomes

[tex]\frac{W_1}{N_1} = \frac{W_2}{N_2}[/tex]

So, we have:

[tex]\frac{37.6\ billion}{483000 } = \frac{W_2}{150000}[/tex]

Multiply both sides by 150000

[tex]W_2 = \frac{37.6\ billion}{483000 } *150000[/tex]

So, we have:

[tex]W_2[/tex] = 11.7 billion

Hence, the amount of water used by a population of 150000 is 11.7 billion