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Finding the Fourth Proportional to 392.61, 540.09 and 318.78

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Solution

The fourth proportional to 392.61, 540.09 and 318.78 is: 438.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    392.61 : 540.09 = 318.78 : x
  2. Step 2: Convert to fraction form
    392.61/540.09 = 318.78/x
  3. Step 3: Cross multiply
    392.61x = 540.09 × 318.78
  4. Step 4: Simplify right side
    392.61x = 172,169.89
  5. Step 5: Solve for x
    x = 172,169.89/392.61
  6. Step 6: Final answer
    x = 438.53

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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.