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Finding the Fourth Proportional to 212.80, 319.12 and 91

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Solution

The fourth proportional to 212.80, 319.12 and 91 is: 136.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.80 : 319.12 = 91 : x
  2. Step 2: Convert to fraction form
    212.80/319.12 = 91/x
  3. Step 3: Cross multiply
    212.80x = 319.12 × 91
  4. Step 4: Simplify right side
    212.80x = 29,039.92
  5. Step 5: Solve for x
    x = 29,039.92/212.80
  6. Step 6: Final answer
    x = 136.47

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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.