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Finding the Third Proportional to 315 and 686.81

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Solution

The third proportional to 315 and 686.81 is: 1,497.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    315 : 686.81 = 686.81 : x
  2. Step 2: Convert to fraction form
    315/686.81 = 686.81/x
  3. Step 3: Cross multiply
    315x = 686.81 × 686.81
  4. Step 4: Simplify right side
    315x = 471,711.41
  5. Step 5: Solve for x
    x = 471,711.41/315
  6. Step 6: Final answer
    x = 1,497.50

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Why These Related Problems?

These problems maintain the same ratio (2.18) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.