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Finding the Fourth Proportional to 429.40, 643.82 and 213.12

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Solution

The fourth proportional to 429.40, 643.82 and 213.12 is: 319.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.40 : 643.82 = 213.12 : x
  2. Step 2: Convert to fraction form
    429.40/643.82 = 213.12/x
  3. Step 3: Cross multiply
    429.40x = 643.82 × 213.12
  4. Step 4: Simplify right side
    429.40x = 137,210.92
  5. Step 5: Solve for x
    x = 137,210.92/429.40
  6. Step 6: Final answer
    x = 319.54

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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.