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Finding the Fourth Proportional to 1,291.66, 1,781.60 and 825.70

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Solution

The fourth proportional to 1,291.66, 1,781.60 and 825.70 is: 1,138.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.66 : 1,781.60 = 825.70 : x
  2. Step 2: Convert to fraction form
    1,291.66/1,781.60 = 825.70/x
  3. Step 3: Cross multiply
    1,291.66x = 1,781.60 × 825.70
  4. Step 4: Simplify right side
    1,291.66x = 1,471,067.12
  5. Step 5: Solve for x
    x = 1,471,067.12/1,291.66
  6. Step 6: Final answer
    x = 1,138.90

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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.