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Finding the Fourth Proportional to 206.98, 310.47 and 85.21

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Solution

The fourth proportional to 206.98, 310.47 and 85.21 is: 127.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.98 : 310.47 = 85.21 : x
  2. Step 2: Convert to fraction form
    206.98/310.47 = 85.21/x
  3. Step 3: Cross multiply
    206.98x = 310.47 × 85.21
  4. Step 4: Simplify right side
    206.98x = 26,455.15
  5. Step 5: Solve for x
    x = 26,455.15/206.98
  6. Step 6: Final answer
    x = 127.82

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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.