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Finding the Fourth Proportional to 390.47, 538.85 and 215.82

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Solution

The fourth proportional to 390.47, 538.85 and 215.82 is: 297.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.47 : 538.85 = 215.82 : x
  2. Step 2: Convert to fraction form
    390.47/538.85 = 215.82/x
  3. Step 3: Cross multiply
    390.47x = 538.85 × 215.82
  4. Step 4: Simplify right side
    390.47x = 116,290.83
  5. Step 5: Solve for x
    x = 116,290.83/390.47
  6. Step 6: Final answer
    x = 297.82

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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.