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Finding the Fourth Proportional to 405.85, 560.46 and 390.82

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Solution

The fourth proportional to 405.85, 560.46 and 390.82 is: 539.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.85 : 560.46 = 390.82 : x
  2. Step 2: Convert to fraction form
    405.85/560.46 = 390.82/x
  3. Step 3: Cross multiply
    405.85x = 560.46 × 390.82
  4. Step 4: Simplify right side
    405.85x = 219,038.98
  5. Step 5: Solve for x
    x = 219,038.98/405.85
  6. Step 6: Final answer
    x = 539.70

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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.