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Finding the Fourth Proportional to 212.72, 319.08 and 90.86

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Solution

The fourth proportional to 212.72, 319.08 and 90.86 is: 136.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.72 : 319.08 = 90.86 : x
  2. Step 2: Convert to fraction form
    212.72/319.08 = 90.86/x
  3. Step 3: Cross multiply
    212.72x = 319.08 × 90.86
  4. Step 4: Simplify right side
    212.72x = 28,990.01
  5. Step 5: Solve for x
    x = 28,990.01/212.72
  6. Step 6: Final answer
    x = 136.29

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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.