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Finding the Fourth Proportional to 318.72, 438.78 and 285.92

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Solution

The fourth proportional to 318.72, 438.78 and 285.92 is: 393.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.72 : 438.78 = 285.92 : x
  2. Step 2: Convert to fraction form
    318.72/438.78 = 285.92/x
  3. Step 3: Cross multiply
    318.72x = 438.78 × 285.92
  4. Step 4: Simplify right side
    318.72x = 125,455.98
  5. Step 5: Solve for x
    x = 125,455.98/318.72
  6. Step 6: Final answer
    x = 393.62

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.