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Finding the Fourth Proportional to 21,240, 31,860 and 8,928

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Solution

The fourth proportional to 21,240, 31,860 and 8,928 is: 13,392

Step by Step Solution

  1. Step 1: Write the proportion equation
    21,240 : 31,860 = 8,928 : x
  2. Step 2: Convert to fraction form
    21,240/31,860 = 8,928/x
  3. Step 3: Cross multiply
    21,240x = 31,860 × 8,928
  4. Step 4: Simplify right side
    21,240x = 284,446,080
  5. Step 5: Solve for x
    x = 284,446,080/21,240
  6. Step 6: Final answer
    x = 13,392

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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.