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Finding the Fourth Proportional to 431.39, 647.12 and 138.93

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Solution

The fourth proportional to 431.39, 647.12 and 138.93 is: 208.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.39 : 647.12 = 138.93 : x
  2. Step 2: Convert to fraction form
    431.39/647.12 = 138.93/x
  3. Step 3: Cross multiply
    431.39x = 647.12 × 138.93
  4. Step 4: Simplify right side
    431.39x = 89,903.69
  5. Step 5: Solve for x
    x = 89,903.69/431.39
  6. Step 6: Final answer
    x = 208.41

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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.