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Finding the Fourth Proportional to 428.44, 643.88 and 212.17

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Solution

The fourth proportional to 428.44, 643.88 and 212.17 is: 318.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.44 : 643.88 = 212.17 : x
  2. Step 2: Convert to fraction form
    428.44/643.88 = 212.17/x
  3. Step 3: Cross multiply
    428.44x = 643.88 × 212.17
  4. Step 4: Simplify right side
    428.44x = 136,612.02
  5. Step 5: Solve for x
    x = 136,612.02/428.44
  6. Step 6: Final answer
    x = 318.86

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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.