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Finding the Fourth Proportional to 312.39, 431.22 and 279.58

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Solution

The fourth proportional to 312.39, 431.22 and 279.58 is: 385.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.39 : 431.22 = 279.58 : x
  2. Step 2: Convert to fraction form
    312.39/431.22 = 279.58/x
  3. Step 3: Cross multiply
    312.39x = 431.22 × 279.58
  4. Step 4: Simplify right side
    312.39x = 120,560.52
  5. Step 5: Solve for x
    x = 120,560.52/312.39
  6. Step 6: Final answer
    x = 385.93

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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.