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Finding the Fourth Proportional to 280.66, 420.94 and 85.62

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Solution

The fourth proportional to 280.66, 420.94 and 85.62 is: 128.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.66 : 420.94 = 85.62 : x
  2. Step 2: Convert to fraction form
    280.66/420.94 = 85.62/x
  3. Step 3: Cross multiply
    280.66x = 420.94 × 85.62
  4. Step 4: Simplify right side
    280.66x = 36,040.88
  5. Step 5: Solve for x
    x = 36,040.88/280.66
  6. Step 6: Final answer
    x = 128.41

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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.