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Finding the Fourth Proportional to 305.20, 420.83 and 287.31

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Solution

The fourth proportional to 305.20, 420.83 and 287.31 is: 396.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.20 : 420.83 = 287.31 : x
  2. Step 2: Convert to fraction form
    305.20/420.83 = 287.31/x
  3. Step 3: Cross multiply
    305.20x = 420.83 × 287.31
  4. Step 4: Simplify right side
    305.20x = 120,909.89
  5. Step 5: Solve for x
    x = 120,909.89/305.20
  6. Step 6: Final answer
    x = 396.16

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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.