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Finding the Fourth Proportional to 1,278.70, 1,764.68 and 781.26

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Solution

The fourth proportional to 1,278.70, 1,764.68 and 781.26 is: 1,078.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.70 : 1,764.68 = 781.26 : x
  2. Step 2: Convert to fraction form
    1,278.70/1,764.68 = 781.26/x
  3. Step 3: Cross multiply
    1,278.70x = 1,764.68 × 781.26
  4. Step 4: Simplify right side
    1,278.70x = 1,378,663.37
  5. Step 5: Solve for x
    x = 1,378,663.37/1,278.70
  6. Step 6: Final answer
    x = 1,078.18

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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.