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Finding the Fourth Proportional to 212.78, 319.19 and 84.50

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Solution

The fourth proportional to 212.78, 319.19 and 84.50 is: 126.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.78 : 319.19 = 84.50 : x
  2. Step 2: Convert to fraction form
    212.78/319.19 = 84.50/x
  3. Step 3: Cross multiply
    212.78x = 319.19 × 84.50
  4. Step 4: Simplify right side
    212.78x = 26,971.56
  5. Step 5: Solve for x
    x = 26,971.56/212.78
  6. Step 6: Final answer
    x = 126.76

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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.