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Finding the Third Proportional to 3.90 and 7.15

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Solution

The third proportional to 3.90 and 7.15 is: 13.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    3.90 : 7.15 = 7.15 : x
  2. Step 2: Convert to fraction form
    3.90/7.15 = 7.15/x
  3. Step 3: Cross multiply
    3.90x = 7.15 × 7.15
  4. Step 4: Simplify right side
    3.90x = 51.15
  5. Step 5: Solve for x
    x = 51.15/3.90
  6. Step 6: Final answer
    x = 13.11

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Why These Related Problems?

These problems maintain the same ratio (1.83) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.