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Finding the Fourth Proportional to 687.86, 1,031.80 and 551.78

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Solution

The fourth proportional to 687.86, 1,031.80 and 551.78 is: 827.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.86 : 1,031.80 = 551.78 : x
  2. Step 2: Convert to fraction form
    687.86/1,031.80 = 551.78/x
  3. Step 3: Cross multiply
    687.86x = 1,031.80 × 551.78
  4. Step 4: Simplify right side
    687.86x = 569,326.60
  5. Step 5: Solve for x
    x = 569,326.60/687.86
  6. Step 6: Final answer
    x = 827.68

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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.