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Finding the Fourth Proportional to 312.68, 431.19 and 281.91

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Solution

The fourth proportional to 312.68, 431.19 and 281.91 is: 388.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.68 : 431.19 = 281.91 : x
  2. Step 2: Convert to fraction form
    312.68/431.19 = 281.91/x
  3. Step 3: Cross multiply
    312.68x = 431.19 × 281.91
  4. Step 4: Simplify right side
    312.68x = 121,558.39
  5. Step 5: Solve for x
    x = 121,558.39/312.68
  6. Step 6: Final answer
    x = 388.77

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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.