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Finding the Fourth Proportional to 278.20, 417.18 and 85.84

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Solution

The fourth proportional to 278.20, 417.18 and 85.84 is: 128.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.20 : 417.18 = 85.84 : x
  2. Step 2: Convert to fraction form
    278.20/417.18 = 85.84/x
  3. Step 3: Cross multiply
    278.20x = 417.18 × 85.84
  4. Step 4: Simplify right side
    278.20x = 35,810.73
  5. Step 5: Solve for x
    x = 35,810.73/278.20
  6. Step 6: Final answer
    x = 128.72

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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.