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Finding the Fourth Proportional to 309.78, 426.54 and 280.47

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Solution

The fourth proportional to 309.78, 426.54 and 280.47 is: 386.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.78 : 426.54 = 280.47 : x
  2. Step 2: Convert to fraction form
    309.78/426.54 = 280.47/x
  3. Step 3: Cross multiply
    309.78x = 426.54 × 280.47
  4. Step 4: Simplify right side
    309.78x = 119,631.67
  5. Step 5: Solve for x
    x = 119,631.67/309.78
  6. Step 6: Final answer
    x = 386.18

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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.