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Finding the Fourth Proportional to 86,430, 129,645 and 20,766

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Solution

The fourth proportional to 86,430, 129,645 and 20,766 is: 31,149

Step by Step Solution

  1. Step 1: Write the proportion equation
    86,430 : 129,645 = 20,766 : x
  2. Step 2: Convert to fraction form
    86,430/129,645 = 20,766/x
  3. Step 3: Cross multiply
    86,430x = 129,645 × 20,766
  4. Step 4: Simplify right side
    86,430x = 2,692,208,070
  5. Step 5: Solve for x
    x = 2,692,208,070/86,430
  6. Step 6: Final answer
    x = 31,149

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.