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Finding the Fourth Proportional to 209.60, 314.42 and 86.21

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Solution

The fourth proportional to 209.60, 314.42 and 86.21 is: 129.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.60 : 314.42 = 86.21 : x
  2. Step 2: Convert to fraction form
    209.60/314.42 = 86.21/x
  3. Step 3: Cross multiply
    209.60x = 314.42 × 86.21
  4. Step 4: Simplify right side
    209.60x = 27,107.58
  5. Step 5: Solve for x
    x = 27,107.58/209.60
  6. Step 6: Final answer
    x = 129.33

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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.