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Finding the Fourth Proportional to 210.80, 315.90 and 129.40

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Solution

The fourth proportional to 210.80, 315.90 and 129.40 is: 193.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.80 : 315.90 = 129.40 : x
  2. Step 2: Convert to fraction form
    210.80/315.90 = 129.40/x
  3. Step 3: Cross multiply
    210.80x = 315.90 × 129.40
  4. Step 4: Simplify right side
    210.80x = 40,876.67
  5. Step 5: Solve for x
    x = 40,876.67/210.80
  6. Step 6: Final answer
    x = 193.91

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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.