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Finding the Fourth Proportional to 428.20, 642.30 and 236.20

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Solution

The fourth proportional to 428.20, 642.30 and 236.20 is: 354.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.20 : 642.30 = 236.20 : x
  2. Step 2: Convert to fraction form
    428.20/642.30 = 236.20/x
  3. Step 3: Cross multiply
    428.20x = 642.30 × 236.20
  4. Step 4: Simplify right side
    428.20x = 151,711.26
  5. Step 5: Solve for x
    x = 151,711.26/428.20
  6. Step 6: Final answer
    x = 354.30

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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.