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Finding the Fourth Proportional to 318.12, 478.44 and 257.40

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Solution

The fourth proportional to 318.12, 478.44 and 257.40 is: 387.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.12 : 478.44 = 257.40 : x
  2. Step 2: Convert to fraction form
    318.12/478.44 = 257.40/x
  3. Step 3: Cross multiply
    318.12x = 478.44 × 257.40
  4. Step 4: Simplify right side
    318.12x = 123,150.46
  5. Step 5: Solve for x
    x = 123,150.46/318.12
  6. Step 6: Final answer
    x = 387.12

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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.