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Finding the Fourth Proportional to 390.52, 538.91 and 215.86

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Solution

The fourth proportional to 390.52, 538.91 and 215.86 is: 297.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.52 : 538.91 = 215.86 : x
  2. Step 2: Convert to fraction form
    390.52/538.91 = 215.86/x
  3. Step 3: Cross multiply
    390.52x = 538.91 × 215.86
  4. Step 4: Simplify right side
    390.52x = 116,328.30
  5. Step 5: Solve for x
    x = 116,328.30/390.52
  6. Step 6: Final answer
    x = 297.88

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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.