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Finding the Fourth Proportional to 8.10, 12.21 and 6.90

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Solution

The fourth proportional to 8.10, 12.21 and 6.90 is: 10.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.10 : 12.21 = 6.90 : x
  2. Step 2: Convert to fraction form
    8.10/12.21 = 6.90/x
  3. Step 3: Cross multiply
    8.10x = 12.21 × 6.90
  4. Step 4: Simplify right side
    8.10x = 84.25
  5. Step 5: Solve for x
    x = 84.25/8.10
  6. Step 6: Final answer
    x = 10.40

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.