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Finding the Fourth Proportional to 209.64, 314.43 and 81.39

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Solution

The fourth proportional to 209.64, 314.43 and 81.39 is: 122.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.64 : 314.43 = 81.39 : x
  2. Step 2: Convert to fraction form
    209.64/314.43 = 81.39/x
  3. Step 3: Cross multiply
    209.64x = 314.43 × 81.39
  4. Step 4: Simplify right side
    209.64x = 25,591.46
  5. Step 5: Solve for x
    x = 25,591.46/209.64
  6. Step 6: Final answer
    x = 122.07

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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.