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Finding the Fourth Proportional to 312.79, 431.31 and 286.33

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Solution

The fourth proportional to 312.79, 431.31 and 286.33 is: 394.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.79 : 431.31 = 286.33 : x
  2. Step 2: Convert to fraction form
    312.79/431.31 = 286.33/x
  3. Step 3: Cross multiply
    312.79x = 431.31 × 286.33
  4. Step 4: Simplify right side
    312.79x = 123,496.99
  5. Step 5: Solve for x
    x = 123,496.99/312.79
  6. Step 6: Final answer
    x = 394.82

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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.