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Finding the Third Proportional to 318.19 and 687.81

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Solution

The third proportional to 318.19 and 687.81 is: 1,486.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.19 : 687.81 = 687.81 : x
  2. Step 2: Convert to fraction form
    318.19/687.81 = 687.81/x
  3. Step 3: Cross multiply
    318.19x = 687.81 × 687.81
  4. Step 4: Simplify right side
    318.19x = 473,086.04
  5. Step 5: Solve for x
    x = 473,086.04/318.19
  6. Step 6: Final answer
    x = 1,486.82

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Why These Related Problems?

These problems maintain the same ratio (2.16) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.