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Finding the Fourth Proportional to 1,387.92, 2,082.42 and 840.51

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Solution

The fourth proportional to 1,387.92, 2,082.42 and 840.51 is: 1,261.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.92 : 2,082.42 = 840.51 : x
  2. Step 2: Convert to fraction form
    1,387.92/2,082.42 = 840.51/x
  3. Step 3: Cross multiply
    1,387.92x = 2,082.42 × 840.51
  4. Step 4: Simplify right side
    1,387.92x = 1,750,294.83
  5. Step 5: Solve for x
    x = 1,750,294.83/1,387.92
  6. Step 6: Final answer
    x = 1,261.09

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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.