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Finding the Fourth Proportional to 426.60, 639.84 and 138

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Solution

The fourth proportional to 426.60, 639.84 and 138 is: 206.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.60 : 639.84 = 138 : x
  2. Step 2: Convert to fraction form
    426.60/639.84 = 138/x
  3. Step 3: Cross multiply
    426.60x = 639.84 × 138
  4. Step 4: Simplify right side
    426.60x = 88,297.92
  5. Step 5: Solve for x
    x = 88,297.92/426.60
  6. Step 6: Final answer
    x = 206.98

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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.