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Finding the Fourth Proportional to 428.84, 643.26 and 212.48

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Solution

The fourth proportional to 428.84, 643.26 and 212.48 is: 318.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.84 : 643.26 = 212.48 : x
  2. Step 2: Convert to fraction form
    428.84/643.26 = 212.48/x
  3. Step 3: Cross multiply
    428.84x = 643.26 × 212.48
  4. Step 4: Simplify right side
    428.84x = 136,679.88
  5. Step 5: Solve for x
    x = 136,679.88/428.84
  6. Step 6: Final answer
    x = 318.72

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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.