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Finding the Fourth Proportional to 1,281.92, 1,767.84 and 840.20

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Solution

The fourth proportional to 1,281.92, 1,767.84 and 840.20 is: 1,158.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.92 : 1,767.84 = 840.20 : x
  2. Step 2: Convert to fraction form
    1,281.92/1,767.84 = 840.20/x
  3. Step 3: Cross multiply
    1,281.92x = 1,767.84 × 840.20
  4. Step 4: Simplify right side
    1,281.92x = 1,485,339.17
  5. Step 5: Solve for x
    x = 1,485,339.17/1,281.92
  6. Step 6: Final answer
    x = 1,158.68

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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.