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Finding the Third Proportional to 686.25 and 987.75

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Solution

The third proportional to 686.25 and 987.75 is: 1,421.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.25 : 987.75 = 987.75 : x
  2. Step 2: Convert to fraction form
    686.25/987.75 = 987.75/x
  3. Step 3: Cross multiply
    686.25x = 987.75 × 987.75
  4. Step 4: Simplify right side
    686.25x = 975,650.06
  5. Step 5: Solve for x
    x = 975,650.06/686.25
  6. Step 6: Final answer
    x = 1,421.71

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Why These Related Problems?

These problems maintain the same ratio (1.44) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.