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Finding the Fourth Proportional to 86,428, 129,642 and 20,764

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Solution

The fourth proportional to 86,428, 129,642 and 20,764 is: 31,146

Step by Step Solution

  1. Step 1: Write the proportion equation
    86,428 : 129,642 = 20,764 : x
  2. Step 2: Convert to fraction form
    86,428/129,642 = 20,764/x
  3. Step 3: Cross multiply
    86,428x = 129,642 × 20,764
  4. Step 4: Simplify right side
    86,428x = 2,691,886,488
  5. Step 5: Solve for x
    x = 2,691,886,488/86,428
  6. Step 6: Final answer
    x = 31,146

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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.