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Finding the Fourth Proportional to 278.88, 418.31 and 86.50

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Solution

The fourth proportional to 278.88, 418.31 and 86.50 is: 129.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.88 : 418.31 = 86.50 : x
  2. Step 2: Convert to fraction form
    278.88/418.31 = 86.50/x
  3. Step 3: Cross multiply
    278.88x = 418.31 × 86.50
  4. Step 4: Simplify right side
    278.88x = 36,183.82
  5. Step 5: Solve for x
    x = 36,183.82/278.88
  6. Step 6: Final answer
    x = 129.75

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.