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Finding the Fourth Proportional to 687.88, 1,031.85 and 415.72

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Solution

The fourth proportional to 687.88, 1,031.85 and 415.72 is: 623.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.88 : 1,031.85 = 415.72 : x
  2. Step 2: Convert to fraction form
    687.88/1,031.85 = 415.72/x
  3. Step 3: Cross multiply
    687.88x = 1,031.85 × 415.72
  4. Step 4: Simplify right side
    687.88x = 428,960.68
  5. Step 5: Solve for x
    x = 428,960.68/687.88
  6. Step 6: Final answer
    x = 623.60

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.