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Finding the Fourth Proportional to 390.49, 538.90 and 215.83

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Solution

The fourth proportional to 390.49, 538.90 and 215.83 is: 297.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.49 : 538.90 = 215.83 : x
  2. Step 2: Convert to fraction form
    390.49/538.90 = 215.83/x
  3. Step 3: Cross multiply
    390.49x = 538.90 × 215.83
  4. Step 4: Simplify right side
    390.49x = 116,308.36
  5. Step 5: Solve for x
    x = 116,308.36/390.49
  6. Step 6: Final answer
    x = 297.86

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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.