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Finding the Fourth Proportional to 278.95, 418.43 and 86.57

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Solution

The fourth proportional to 278.95, 418.43 and 86.57 is: 129.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.95 : 418.43 = 86.57 : x
  2. Step 2: Convert to fraction form
    278.95/418.43 = 86.57/x
  3. Step 3: Cross multiply
    278.95x = 418.43 × 86.57
  4. Step 4: Simplify right side
    278.95x = 36,223.49
  5. Step 5: Solve for x
    x = 36,223.49/278.95
  6. Step 6: Final answer
    x = 129.86

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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.