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Finding the Fourth Proportional to 390.31, 538.63 and 215.66

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Solution

The fourth proportional to 390.31, 538.63 and 215.66 is: 297.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.31 : 538.63 = 215.66 : x
  2. Step 2: Convert to fraction form
    390.31/538.63 = 215.66/x
  3. Step 3: Cross multiply
    390.31x = 538.63 × 215.66
  4. Step 4: Simplify right side
    390.31x = 116,160.14
  5. Step 5: Solve for x
    x = 116,160.14/390.31
  6. Step 6: Final answer
    x = 297.61

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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.