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Finding the Fourth Proportional to 209.88, 314.58 and 81.56

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Solution

The fourth proportional to 209.88, 314.58 and 81.56 is: 122.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.88 : 314.58 = 81.56 : x
  2. Step 2: Convert to fraction form
    209.88/314.58 = 81.56/x
  3. Step 3: Cross multiply
    209.88x = 314.58 × 81.56
  4. Step 4: Simplify right side
    209.88x = 25,657.14
  5. Step 5: Solve for x
    x = 25,657.14/209.88
  6. Step 6: Final answer
    x = 122.25

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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.