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Finding the Fourth Proportional to 210.75, 315.78 and 129.61

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Solution

The fourth proportional to 210.75, 315.78 and 129.61 is: 194.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.75 : 315.78 = 129.61 : x
  2. Step 2: Convert to fraction form
    210.75/315.78 = 129.61/x
  3. Step 3: Cross multiply
    210.75x = 315.78 × 129.61
  4. Step 4: Simplify right side
    210.75x = 40,928.25
  5. Step 5: Solve for x
    x = 40,928.25/210.75
  6. Step 6: Final answer
    x = 194.20

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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.