Math Problem Statement

A swimming pool is being drained at a constant rate of 15 gallons per minute. The pool initially holds 1,200 gallons of water.

Which equation represents the amount of water, g , left in the pool after t minutes? A.t=−15g+1,200

B.g=15t−1,200

C.g=−15t+1,200

D.t=15g+1,200

Solution

Let's break this problem down step-by-step.

We are given:

  • Rate of drainage: 15 gallons per minute (constant).
  • Initial water: 1,200 gallons.
  • We need to find an equation that expresses the amount of water gg left in the pool after tt minutes.

Step 1: Understanding the relationship

  • At t=0t = 0, the pool has 1,200 gallons.
  • For every minute tt, 15 gallons are removed, meaning the amount of water decreases linearly.

The decrease in water can be expressed as: Water left=Initial amount(Rate×Time)\text{Water left} = \text{Initial amount} - (\text{Rate} \times \text{Time}) g=1,20015tg = 1,200 - 15t

Step 2: Rewriting the equation

The correct form matches: g=15t+1,200g = -15t + 1,200

This equation tells us that as time tt increases, the amount of water gg decreases by 15 gallons per minute.

Step 3: Identify the correct option

The correct option is:

C. g=15t+1,200g = -15t + 1,200


Would you like to see more examples of similar problems?

Here are 5 follow-up questions to practice:

  1. How much water will be left after 30 minutes?
  2. How long will it take to completely drain the pool?
  3. What would the equation be if the pool started with 1,500 gallons instead?
  4. If the rate of drainage was 20 gallons per minute, how would the equation change?
  5. What does the slope of the equation represent in this problem?

Tip: The slope in a linear equation often represents the rate of change—in this case, the gallons lost per minute.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Rate of Change
Algebra

Formulas

g = -15t + 1,200 (linear equation for remaining water)

Theorems

Linear Function Theorem

Suitable Grade Level

Grades 6-8