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Finding the Fourth Proportional to 428.68, 642.90 and 140.32

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Solution

The fourth proportional to 428.68, 642.90 and 140.32 is: 210.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.68 : 642.90 = 140.32 : x
  2. Step 2: Convert to fraction form
    428.68/642.90 = 140.32/x
  3. Step 3: Cross multiply
    428.68x = 642.90 × 140.32
  4. Step 4: Simplify right side
    428.68x = 90,211.73
  5. Step 5: Solve for x
    x = 90,211.73/428.68
  6. Step 6: Final answer
    x = 210.44

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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.