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Finding the Fourth Proportional to 318.40, 478.10 and 256.91

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Solution

The fourth proportional to 318.40, 478.10 and 256.91 is: 385.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.40 : 478.10 = 256.91 : x
  2. Step 2: Convert to fraction form
    318.40/478.10 = 256.91/x
  3. Step 3: Cross multiply
    318.40x = 478.10 × 256.91
  4. Step 4: Simplify right side
    318.40x = 122,826.92
  5. Step 5: Solve for x
    x = 122,826.92/318.40
  6. Step 6: Final answer
    x = 385.77

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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.