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Finding the Fourth Proportional to 209.21, 313.91 and 87.45

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Solution

The fourth proportional to 209.21, 313.91 and 87.45 is: 131.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.21 : 313.91 = 87.45 : x
  2. Step 2: Convert to fraction form
    209.21/313.91 = 87.45/x
  3. Step 3: Cross multiply
    209.21x = 313.91 × 87.45
  4. Step 4: Simplify right side
    209.21x = 27,450.99
  5. Step 5: Solve for x
    x = 27,450.99/209.21
  6. Step 6: Final answer
    x = 131.22

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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.