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Finding the Fourth Proportional to 212.39, 318 and 139.05

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Solution

The fourth proportional to 212.39, 318 and 139.05 is: 208.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.39 : 318 = 139.05 : x
  2. Step 2: Convert to fraction form
    212.39/318 = 139.05/x
  3. Step 3: Cross multiply
    212.39x = 318 × 139.05
  4. Step 4: Simplify right side
    212.39x = 44,217.90
  5. Step 5: Solve for x
    x = 44,217.90/212.39
  6. Step 6: Final answer
    x = 208.19

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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.