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Finding the Fourth Proportional to 278.58, 417.86 and 86.20

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Solution

The fourth proportional to 278.58, 417.86 and 86.20 is: 129.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.58 : 417.86 = 86.20 : x
  2. Step 2: Convert to fraction form
    278.58/417.86 = 86.20/x
  3. Step 3: Cross multiply
    278.58x = 417.86 × 86.20
  4. Step 4: Simplify right side
    278.58x = 36,019.53
  5. Step 5: Solve for x
    x = 36,019.53/278.58
  6. Step 6: Final answer
    x = 129.30

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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.