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Finding the Fourth Proportional to 431.55, 647.01 and 138.95

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Solution

The fourth proportional to 431.55, 647.01 and 138.95 is: 208.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.55 : 647.01 = 138.95 : x
  2. Step 2: Convert to fraction form
    431.55/647.01 = 138.95/x
  3. Step 3: Cross multiply
    431.55x = 647.01 × 138.95
  4. Step 4: Simplify right side
    431.55x = 89,898.80
  5. Step 5: Solve for x
    x = 89,898.80/431.55
  6. Step 6: Final answer
    x = 208.32

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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.