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Finding the Fourth Proportional to 10.20, 15.31 and 6.40

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Solution

The fourth proportional to 10.20, 15.31 and 6.40 is: 9.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    10.20 : 15.31 = 6.40 : x
  2. Step 2: Convert to fraction form
    10.20/15.31 = 6.40/x
  3. Step 3: Cross multiply
    10.20x = 15.31 × 6.40
  4. Step 4: Simplify right side
    10.20x = 97.98
  5. Step 5: Solve for x
    x = 97.98/10.20
  6. Step 6: Final answer
    x = 9.61

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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.