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Finding the Fourth Proportional to 405.18, 559.40 and 287.40

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Solution

The fourth proportional to 405.18, 559.40 and 287.40 is: 396.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.18 : 559.40 = 287.40 : x
  2. Step 2: Convert to fraction form
    405.18/559.40 = 287.40/x
  3. Step 3: Cross multiply
    405.18x = 559.40 × 287.40
  4. Step 4: Simplify right side
    405.18x = 160,771.56
  5. Step 5: Solve for x
    x = 160,771.56/405.18
  6. Step 6: Final answer
    x = 396.79

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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.