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Finding the Fourth Proportional to 278.89, 418.35 and 86.50

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Solution

The fourth proportional to 278.89, 418.35 and 86.50 is: 129.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.89 : 418.35 = 86.50 : x
  2. Step 2: Convert to fraction form
    278.89/418.35 = 86.50/x
  3. Step 3: Cross multiply
    278.89x = 418.35 × 86.50
  4. Step 4: Simplify right side
    278.89x = 36,187.28
  5. Step 5: Solve for x
    x = 36,187.28/278.89
  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.