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Finding the Fourth Proportional to 209.20, 313.67 and 87.40

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Solution

The fourth proportional to 209.20, 313.67 and 87.40 is: 131.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.20 : 313.67 = 87.40 : x
  2. Step 2: Convert to fraction form
    209.20/313.67 = 87.40/x
  3. Step 3: Cross multiply
    209.20x = 313.67 × 87.40
  4. Step 4: Simplify right side
    209.20x = 27,414.76
  5. Step 5: Solve for x
    x = 27,414.76/209.20
  6. Step 6: Final answer
    x = 131.05

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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.