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Finding the Fourth Proportional to 278.20, 417.36 and 85.80

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Solution

The fourth proportional to 278.20, 417.36 and 85.80 is: 128.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.20 : 417.36 = 85.80 : x
  2. Step 2: Convert to fraction form
    278.20/417.36 = 85.80/x
  3. Step 3: Cross multiply
    278.20x = 417.36 × 85.80
  4. Step 4: Simplify right side
    278.20x = 35,809.49
  5. Step 5: Solve for x
    x = 35,809.49/278.20
  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.