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Finding the Fourth Proportional to 428.08, 641.75 and 135.40

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Solution

The fourth proportional to 428.08, 641.75 and 135.40 is: 202.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.08 : 641.75 = 135.40 : x
  2. Step 2: Convert to fraction form
    428.08/641.75 = 135.40/x
  3. Step 3: Cross multiply
    428.08x = 641.75 × 135.40
  4. Step 4: Simplify right side
    428.08x = 86,891.68
  5. Step 5: Solve for x
    x = 86,891.68/428.08
  6. Step 6: Final answer
    x = 202.98

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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.