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Finding the Fourth Proportional to 428.04, 642.12 and 139.52

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Solution

The fourth proportional to 428.04, 642.12 and 139.52 is: 209.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.04 : 642.12 = 139.52 : x
  2. Step 2: Convert to fraction form
    428.04/642.12 = 139.52/x
  3. Step 3: Cross multiply
    428.04x = 642.12 × 139.52
  4. Step 4: Simplify right side
    428.04x = 89,588.58
  5. Step 5: Solve for x
    x = 89,588.58/428.04
  6. Step 6: Final answer
    x = 209.30

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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.