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Finding the Fourth Proportional to 21,856, 30,161.28 and 11,920

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Solution

The fourth proportional to 21,856, 30,161.28 and 11,920 is: 16,449.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    21,856 : 30,161.28 = 11,920 : x
  2. Step 2: Convert to fraction form
    21,856/30,161.28 = 11,920/x
  3. Step 3: Cross multiply
    21,856x = 30,161.28 × 11,920
  4. Step 4: Simplify right side
    21,856x = 359,522,457.60
  5. Step 5: Solve for x
    x = 359,522,457.60/21,856
  6. Step 6: Final answer
    x = 16,449.60

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.