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Finding the Fourth Proportional to 428, 642 and 196.20

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Solution

The fourth proportional to 428, 642 and 196.20 is: 294.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    428 : 642 = 196.20 : x
  2. Step 2: Convert to fraction form
    428/642 = 196.20/x
  3. Step 3: Cross multiply
    428x = 642 × 196.20
  4. Step 4: Simplify right side
    428x = 125,960.40
  5. Step 5: Solve for x
    x = 125,960.40/428
  6. Step 6: Final answer
    x = 294.30

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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.