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Finding the Fourth Proportional to 9.21, 12.71 and 6.45

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Solution

The fourth proportional to 9.21, 12.71 and 6.45 is: 8.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    9.21 : 12.71 = 6.45 : x
  2. Step 2: Convert to fraction form
    9.21/12.71 = 6.45/x
  3. Step 3: Cross multiply
    9.21x = 12.71 × 6.45
  4. Step 4: Simplify right side
    9.21x = 81.98
  5. Step 5: Solve for x
    x = 81.98/9.21
  6. Step 6: Final answer
    x = 8.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.