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Finding the Fourth Proportional to 431.70, 647.63 and 139.26

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Solution

The fourth proportional to 431.70, 647.63 and 139.26 is: 208.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.70 : 647.63 = 139.26 : x
  2. Step 2: Convert to fraction form
    431.70/647.63 = 139.26/x
  3. Step 3: Cross multiply
    431.70x = 647.63 × 139.26
  4. Step 4: Simplify right side
    431.70x = 90,188.26
  5. Step 5: Solve for x
    x = 90,188.26/431.70
  6. Step 6: Final answer
    x = 208.91

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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.