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Finding the Fourth Proportional to 687.68, 1,031.20 and 254.72

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Solution

The fourth proportional to 687.68, 1,031.20 and 254.72 is: 381.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.68 : 1,031.20 = 254.72 : x
  2. Step 2: Convert to fraction form
    687.68/1,031.20 = 254.72/x
  3. Step 3: Cross multiply
    687.68x = 1,031.20 × 254.72
  4. Step 4: Simplify right side
    687.68x = 262,667.26
  5. Step 5: Solve for x
    x = 262,667.26/687.68
  6. Step 6: Final answer
    x = 381.96

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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.