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Finding the Fourth Proportional to 428.63, 642.81 and 140

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Solution

The fourth proportional to 428.63, 642.81 and 140 is: 209.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.63 : 642.81 = 140 : x
  2. Step 2: Convert to fraction form
    428.63/642.81 = 140/x
  3. Step 3: Cross multiply
    428.63x = 642.81 × 140
  4. Step 4: Simplify right side
    428.63x = 89,993.40
  5. Step 5: Solve for x
    x = 89,993.40/428.63
  6. Step 6: Final answer
    x = 209.96

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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.