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Finding the Fourth Proportional to 209.39, 313.90 and 87.57

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Solution

The fourth proportional to 209.39, 313.90 and 87.57 is: 131.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.39 : 313.90 = 87.57 : x
  2. Step 2: Convert to fraction form
    209.39/313.90 = 87.57/x
  3. Step 3: Cross multiply
    209.39x = 313.90 × 87.57
  4. Step 4: Simplify right side
    209.39x = 27,488.22
  5. Step 5: Solve for x
    x = 27,488.22/209.39
  6. Step 6: Final answer
    x = 131.28

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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.