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Finding the Fourth Proportional to 687.76, 1,031.33 and 619.92

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Solution

The fourth proportional to 687.76, 1,031.33 and 619.92 is: 929.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.76 : 1,031.33 = 619.92 : x
  2. Step 2: Convert to fraction form
    687.76/1,031.33 = 619.92/x
  3. Step 3: Cross multiply
    687.76x = 1,031.33 × 619.92
  4. Step 4: Simplify right side
    687.76x = 639,343.64
  5. Step 5: Solve for x
    x = 639,343.64/687.76
  6. Step 6: Final answer
    x = 929.61

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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.