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Finding the Fourth Proportional to 312.62, 431.78 and 280.04

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Solution

The fourth proportional to 312.62, 431.78 and 280.04 is: 386.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.62 : 431.78 = 280.04 : x
  2. Step 2: Convert to fraction form
    312.62/431.78 = 280.04/x
  3. Step 3: Cross multiply
    312.62x = 431.78 × 280.04
  4. Step 4: Simplify right side
    312.62x = 120,915.67
  5. Step 5: Solve for x
    x = 120,915.67/312.62
  6. Step 6: Final answer
    x = 386.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.