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Finding the Fourth Proportional to 431.82, 647.64 and 139.32

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Solution

The fourth proportional to 431.82, 647.64 and 139.32 is: 208.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.82 : 647.64 = 139.32 : x
  2. Step 2: Convert to fraction form
    431.82/647.64 = 139.32/x
  3. Step 3: Cross multiply
    431.82x = 647.64 × 139.32
  4. Step 4: Simplify right side
    431.82x = 90,229.20
  5. Step 5: Solve for x
    x = 90,229.20/431.82
  6. Step 6: Final answer
    x = 208.95

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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.