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Finding the Fourth Proportional to 428.30, 641.22 and 318.40

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Solution

The fourth proportional to 428.30, 641.22 and 318.40 is: 476.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.30 : 641.22 = 318.40 : x
  2. Step 2: Convert to fraction form
    428.30/641.22 = 318.40/x
  3. Step 3: Cross multiply
    428.30x = 641.22 × 318.40
  4. Step 4: Simplify right side
    428.30x = 204,164.45
  5. Step 5: Solve for x
    x = 204,164.45/428.30
  6. Step 6: Final answer
    x = 476.69

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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.