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Finding the Fourth Proportional to 280.23, 420.39 and 85.23

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Solution

The fourth proportional to 280.23, 420.39 and 85.23 is: 127.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.23 : 420.39 = 85.23 : x
  2. Step 2: Convert to fraction form
    280.23/420.39 = 85.23/x
  3. Step 3: Cross multiply
    280.23x = 420.39 × 85.23
  4. Step 4: Simplify right side
    280.23x = 35,829.84
  5. Step 5: Solve for x
    x = 35,829.84/280.23
  6. Step 6: Final answer
    x = 127.86

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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.