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Finding the Fourth Proportional to 212.91, 319.15 and 91.25

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Solution

The fourth proportional to 212.91, 319.15 and 91.25 is: 136.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.91 : 319.15 = 91.25 : x
  2. Step 2: Convert to fraction form
    212.91/319.15 = 91.25/x
  3. Step 3: Cross multiply
    212.91x = 319.15 × 91.25
  4. Step 4: Simplify right side
    212.91x = 29,122.44
  5. Step 5: Solve for x
    x = 29,122.44/212.91
  6. Step 6: Final answer
    x = 136.78

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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.