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Finding the Fourth Proportional to 212.56, 318.72 and 84.28

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Solution

The fourth proportional to 212.56, 318.72 and 84.28 is: 126.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.56 : 318.72 = 84.28 : x
  2. Step 2: Convert to fraction form
    212.56/318.72 = 84.28/x
  3. Step 3: Cross multiply
    212.56x = 318.72 × 84.28
  4. Step 4: Simplify right side
    212.56x = 26,861.72
  5. Step 5: Solve for x
    x = 26,861.72/212.56
  6. Step 6: Final answer
    x = 126.37

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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.