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Finding the Third Proportional to 4.21 and 7.81

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Solution

The third proportional to 4.21 and 7.81 is: 14.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    4.21 : 7.81 = 7.81 : x
  2. Step 2: Convert to fraction form
    4.21/7.81 = 7.81/x
  3. Step 3: Cross multiply
    4.21x = 7.81 × 7.81
  4. Step 4: Simplify right side
    4.21x = 61.01
  5. Step 5: Solve for x
    x = 61.01/4.21
  6. Step 6: Final answer
    x = 14.49

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Why These Related Problems?

These problems maintain the same ratio (1.86) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.