SOLUTION: The water usage in a city varies directly with the population of a city. City A has a population of 225,000 people and uses an average of 28,925,000 gallons of water per day. How

Algebra ->  Volume -> SOLUTION: The water usage in a city varies directly with the population of a city. City A has a population of 225,000 people and uses an average of 28,925,000 gallons of water per day. How      Log On


   



Question 1058017: The water usage in a city varies directly with the population of a city. City A has a population of 225,000 people and uses an average of 28,925,000 gallons of water per day. How many gallons of water per day should we expect City B to produce if its population is 4,890,000 people?



Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = gallons/day of water city B uses
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(1) +28925000+%2F+225000+=+x+%2F+4890000+
Divide top and bottom of the left side
by +25000+
+1157+%2F+9+=+x+%2F+4890000+
Multiply both sides by +9%2A4890000+
+1157%2A4890000+=+9x+
+9x+=+5657730000+
+x+=+628636666.7+
City B will use 628,636,666.7 gallons/day
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check:
Take the logs of both sides of (1)
(1) +log%28+28925000+%29+-+log%28+225000+%29+=+log%28+628636666.7+%29+-+log%28+4890000+%29+
(1) +7.461273368+-+5.352182518+=+8.798399709+-+6.689308859+
(1) +2.10909085+=+2.10909085+
OK