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Finding the Third Proportional to 21 and 55

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Solution

The third proportional to 21 and 55 is: 144.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    21 : 55 = 55 : x
  2. Step 2: Convert to fraction form
    21/55 = 55/x
  3. Step 3: Cross multiply
    21x = 55 × 55
  4. Step 4: Simplify right side
    21x = 3,025
  5. Step 5: Solve for x
    x = 3,025/21
  6. Step 6: Final answer
    x = 144.05

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Why These Related Problems?

These problems maintain the same ratio (2.62) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.