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If an initial quantity $\"\"$ grove or decays at an exponential rate $\"\"$ or $\"\"$ , then the final amount $\"\"$ after a time $\"\"$ is given by the following formula $\"\"$ . $\"\"$

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(a)

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Find the average cost of gasoline increased at an exponential rate.

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Time period between $\"\"$ and $\"\"$ is $\"\"$ .

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Here, $\"\"$ , $\"\"$ and $\"\"$ .

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Consider $\"\"$ .

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Substitute the corresponding values in above equation.

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$\"\"$

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$\"\"$

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$\"\"$ .

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Exponential equation is $\"\"$ .

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$\"\"$

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(b)

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Find average cost of gallon of gasoline in $\"\"$ and $\"\"$ .

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Time period between $\"\"$ and $\"\"$ is $\"\"$ .

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Here, $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$

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Average cost of gasoline in $\"\"$ is $\"\"$ .

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Time period between $\"\"$ and $\"\"$ is $\"\"$ .

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Here, $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$ .

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Average cost of gasoline in $\"\"$ is $\"\"$ .

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$\"\"$

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(c)

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Find when average cost of a gallon of a gasoline exceeds $\"\"$ .

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Here, $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$

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Apply logarithm on each side.

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$\"\"$

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$\"\"$ .

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Average cost of a gallon of gasoline exceeds $\"\"$ after $\"\"$ years, i.e after $\"\"$ .

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$\"\"$

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(d)

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We have so many factors to change gasoline prices.

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$\"\"$

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(a) Exponential equation is $\"\"$ .

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(b)

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Average cost of gasoline in $\"\"$ is $\"\"$ .

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Average cost of gasoline in $\"\"$ is $\"\"$ .

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(c) Average cost of a gallon of gasoline exceeds $\"\"$ after $\"\"$ years, i.e after $\"\"$ .

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(d) We have so many factors to change gasoline prices.