A water sprinkler uses 12.9 gallons of water per minute. How many gallons of water will it use in 36.5 minutes?

Solution Procedure

Considering the spool as a cylindrical shape, and calculating the circumference based on the area cited, we establish the connection between circumference and area as follows:

... C = 2√(πA)

To find ten times this circumference, we calculate:

... 10C = 20√(π·20 cm²) = 40√(5π) cm ≈ 159 cm

Derivation of Formulas

The standard formulas for circumference and area are:

... C = 2πr

... A = πr²

Multiplying the area formula by π and extracting the square root yields:

... πA = (πr)²

... √(πA) = πr

Doubling this value results in the circumference formula:

... C = 2√(πA) = 2πr

a(t) = 210 - 5t

(1) What does t represent?

Since t is given in minutes, it stands for time.

Interpreting t as the balloon’s altitude is incorrect since a(t) represents altitude.

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Time elapsed since the balloon starts descending

This is the correct interpretation.

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Time for the balloon to reach ground level is incorrect because that would be a fixed moment, not a variable t.

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(2) What does a(t) represent?

The balloon’s altitude

This is the correct answer.

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Time since descent began is incorrect because that is represented by t.

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Time to reach the ground is inaccurate since a(t) is altitude, not time.

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(3) What does a(5.5) signify?

It does not represent the time to reach 5.5 feet altitude.

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The altitude of the balloon after 5.5 minutes

This is the correct interpretation since a(5.5) is altitude when t = 5.5 minutes.

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It is not the time needed to reach the ground.

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5.5 minutes alone is not correct because a(t) denotes altitude, not time.

a(5.5) refers to altitude at t = 5.5 minutes.

The answer is found by dividing the total pages by the total time in minutes.

Calculating 7.5 divided by 9 equals approximately 0.8333, so Monica reads around 0.83 pages each minute on average.

I also require the answer!