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Finding the Fourth Proportional to 309.91, 428.01 and 211.49

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Solution

The fourth proportional to 309.91, 428.01 and 211.49 is: 292.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.91 : 428.01 = 211.49 : x
  2. Step 2: Convert to fraction form
    309.91/428.01 = 211.49/x
  3. Step 3: Cross multiply
    309.91x = 428.01 × 211.49
  4. Step 4: Simplify right side
    309.91x = 90,519.83
  5. Step 5: Solve for x
    x = 90,519.83/309.91
  6. Step 6: Final answer
    x = 292.08

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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.