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Finding the Fourth Proportional to 311.40, 429.78 and 213.12

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Solution

The fourth proportional to 311.40, 429.78 and 213.12 is: 294.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.40 : 429.78 = 213.12 : x
  2. Step 2: Convert to fraction form
    311.40/429.78 = 213.12/x
  3. Step 3: Cross multiply
    311.40x = 429.78 × 213.12
  4. Step 4: Simplify right side
    311.40x = 91,594.71
  5. Step 5: Solve for x
    x = 91,594.71/311.40
  6. Step 6: Final answer
    x = 294.14

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.