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Finding the Third Proportional to 15,687 and 21,987

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Solution

The third proportional to 15,687 and 21,987 is: 30,817.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    15,687 : 21,987 = 21,987 : x
  2. Step 2: Convert to fraction form
    15,687/21,987 = 21,987/x
  3. Step 3: Cross multiply
    15,687x = 21,987 × 21,987
  4. Step 4: Simplify right side
    15,687x = 483,428,169
  5. Step 5: Solve for x
    x = 483,428,169/15,687
  6. Step 6: Final answer
    x = 30,817.12

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Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.