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Finding the Fourth Proportional to 390.56, 585.45 and 217.31

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Solution

The fourth proportional to 390.56, 585.45 and 217.31 is: 325.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.56 : 585.45 = 217.31 : x
  2. Step 2: Convert to fraction form
    390.56/585.45 = 217.31/x
  3. Step 3: Cross multiply
    390.56x = 585.45 × 217.31
  4. Step 4: Simplify right side
    390.56x = 127,221.21
  5. Step 5: Solve for x
    x = 127,221.21/390.56
  6. Step 6: Final answer
    x = 325.74

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.