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Finding the Fourth Proportional to 206.90, 310.21 and 138.23

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Solution

The fourth proportional to 206.90, 310.21 and 138.23 is: 207.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.90 : 310.21 = 138.23 : x
  2. Step 2: Convert to fraction form
    206.90/310.21 = 138.23/x
  3. Step 3: Cross multiply
    206.90x = 310.21 × 138.23
  4. Step 4: Simplify right side
    206.90x = 42,879.59
  5. Step 5: Solve for x
    x = 42,879.59/206.90
  6. Step 6: Final answer
    x = 207.25

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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.