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Finding the Fourth Proportional to 1,388.59, 2,081.85 and 840.64

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Solution

The fourth proportional to 1,388.59, 2,081.85 and 840.64 is: 1,260.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.59 : 2,081.85 = 840.64 : x
  2. Step 2: Convert to fraction form
    1,388.59/2,081.85 = 840.64/x
  3. Step 3: Cross multiply
    1,388.59x = 2,081.85 × 840.64
  4. Step 4: Simplify right side
    1,388.59x = 1,750,086.38
  5. Step 5: Solve for x
    x = 1,750,086.38/1,388.59
  6. Step 6: Final answer
    x = 1,260.33

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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.