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Finding the Fourth Proportional to 389.78, 537.90 and 215.12

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Solution

The fourth proportional to 389.78, 537.90 and 215.12 is: 296.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.78 : 537.90 = 215.12 : x
  2. Step 2: Convert to fraction form
    389.78/537.90 = 215.12/x
  3. Step 3: Cross multiply
    389.78x = 537.90 × 215.12
  4. Step 4: Simplify right side
    389.78x = 115,713.05
  5. Step 5: Solve for x
    x = 115,713.05/389.78
  6. Step 6: Final answer
    x = 296.87

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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.