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Finding the Fourth Proportional to 431.79, 647.79 and 139.29

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Solution

The fourth proportional to 431.79, 647.79 and 139.29 is: 208.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.79 : 647.79 = 139.29 : x
  2. Step 2: Convert to fraction form
    431.79/647.79 = 139.29/x
  3. Step 3: Cross multiply
    431.79x = 647.79 × 139.29
  4. Step 4: Simplify right side
    431.79x = 90,230.67
  5. Step 5: Solve for x
    x = 90,230.67/431.79
  6. Step 6: Final answer
    x = 208.97

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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.