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Finding the Fourth Proportional to 431.29, 647.02 and 138.80

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Solution

The fourth proportional to 431.29, 647.02 and 138.80 is: 208.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.29 : 647.02 = 138.80 : x
  2. Step 2: Convert to fraction form
    431.29/647.02 = 138.80/x
  3. Step 3: Cross multiply
    431.29x = 647.02 × 138.80
  4. Step 4: Simplify right side
    431.29x = 89,806.38
  5. Step 5: Solve for x
    x = 89,806.38/431.29
  6. Step 6: Final answer
    x = 208.23

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These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.