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Finding the Fourth Proportional to 390.56, 539.12 and 243.20

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Solution

The fourth proportional to 390.56, 539.12 and 243.20 is: 335.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.56 : 539.12 = 243.20 : x
  2. Step 2: Convert to fraction form
    390.56/539.12 = 243.20/x
  3. Step 3: Cross multiply
    390.56x = 539.12 × 243.20
  4. Step 4: Simplify right side
    390.56x = 131,115.94
  5. Step 5: Solve for x
    x = 131,115.94/390.56
  6. Step 6: Final answer
    x = 335.72

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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.