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Finding the Fourth Proportional to 209.99, 315.09 and 128.99

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Solution

The fourth proportional to 209.99, 315.09 and 128.99 is: 193.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.99 : 315.09 = 128.99 : x
  2. Step 2: Convert to fraction form
    209.99/315.09 = 128.99/x
  3. Step 3: Cross multiply
    209.99x = 315.09 × 128.99
  4. Step 4: Simplify right side
    209.99x = 40,644.25
  5. Step 5: Solve for x
    x = 40,644.25/209.99
  6. Step 6: Final answer
    x = 193.55

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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.