Question

Difficulty: MediumInverse Proportions

Match each inverse proportion scenario to its correct calculated value.

  • Base rations feed 500500 troops for 30 days30\text{ days}. How long will the same rations last for 750750 troops?20 days20\text{ days}
  • A transport plane traveling at 400 mph400\text{ mph} completes a route in 6 hours6\text{ hours}. How long will the flight take at 600 mph600\text{ mph}?4 hours4\text{ hours}
  • A detail of 1212 sailors paints a deck in 8 hours8\text{ hours}. How long will it take 1616 sailors working at the same rate?6 hours6\text{ hours}
  • A 6060-tooth gear spins at 120 RPM120\text{ RPM}. What is the rotational speed of a connected 4545-tooth gear?160 RPM160\text{ RPM}

Answer

Each scenario represents an inverse proportion and must be matched with the value that maintains the constant product of the initial conditions.
Each match is mathematically determined by setting up an inverse proportion equation where the product of the initial states equals the product of the final states (x1⋅y1=x2⋅y2x_1 \cdot y_1 = x_2 \cdot y_2). Dividing the initial product by the new given value provides the correct corresponding answer.

Step-by-Step Solution

1
Identify that each scenario represents an inverse relationship.
As one quantity increases (troops, speed, workers, gear teeth), the other quantity must decrease.
This determines that the product of the variables is constant (x1⋅y1=x2⋅y2x_1 \cdot y_1 = x_2 \cdot y_2), rather than the ratio.
2
Calculate the constant product (kk) for the initial conditions in each scenario.
The constants are 15,00015,000 troop-days, 2,400 miles2,400\text{ miles}, 96 man-hours96\text{ man-hours}, and 7,200 teeth-RPM7,200\text{ teeth-RPM}.
The constant represents the total amount of work, distance, resources, or mechanical transfer that must remain unchanged.
3
Divide the constant product by the new given variable to find the unknown required value.
The resulting values are 20 days20\text{ days}, 4 hours4\text{ hours}, 6 hours6\text{ hours}, and 160 RPM160\text{ RPM}.
Solving the equation x1⋅y1=x2⋅y2x_1 \cdot y_1 = x_2 \cdot y_2 for the unknown variable y2y_2 requires dividing the constant by x2x_2.

Key Concept

Inverse Proportions
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