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Finding the Fourth Proportional to 1,392, 1,921.92 and 840.96

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Solution

The fourth proportional to 1,392, 1,921.92 and 840.96 is: 1,161.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,392 : 1,921.92 = 840.96 : x
  2. Step 2: Convert to fraction form
    1,392/1,921.92 = 840.96/x
  3. Step 3: Cross multiply
    1,392x = 1,921.92 × 840.96
  4. Step 4: Simplify right side
    1,392x = 1,616,257.84
  5. Step 5: Solve for x
    x = 1,616,257.84/1,392
  6. Step 6: Final answer
    x = 1,161.10

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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.