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Finding the Fourth Proportional to 86,454, 129,681 and 20,790

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Solution

The fourth proportional to 86,454, 129,681 and 20,790 is: 31,185

Step by Step Solution

  1. Step 1: Write the proportion equation
    86,454 : 129,681 = 20,790 : x
  2. Step 2: Convert to fraction form
    86,454/129,681 = 20,790/x
  3. Step 3: Cross multiply
    86,454x = 129,681 × 20,790
  4. Step 4: Simplify right side
    86,454x = 2,696,067,990
  5. Step 5: Solve for x
    x = 2,696,067,990/86,454
  6. Step 6: Final answer
    x = 31,185

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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.