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Finding the Fourth Proportional to 212.88, 319.38 and 91.22

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Solution

The fourth proportional to 212.88, 319.38 and 91.22 is: 136.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.88 : 319.38 = 91.22 : x
  2. Step 2: Convert to fraction form
    212.88/319.38 = 91.22/x
  3. Step 3: Cross multiply
    212.88x = 319.38 × 91.22
  4. Step 4: Simplify right side
    212.88x = 29,133.84
  5. Step 5: Solve for x
    x = 29,133.84/212.88
  6. Step 6: Final answer
    x = 136.86

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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.