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Finding the Fourth Proportional to 209.88, 314.81 and 79.87

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Solution

The fourth proportional to 209.88, 314.81 and 79.87 is: 119.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.88 : 314.81 = 79.87 : x
  2. Step 2: Convert to fraction form
    209.88/314.81 = 79.87/x
  3. Step 3: Cross multiply
    209.88x = 314.81 × 79.87
  4. Step 4: Simplify right side
    209.88x = 25,143.87
  5. Step 5: Solve for x
    x = 25,143.87/209.88
  6. Step 6: Final answer
    x = 119.80

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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.