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Finding the Fourth Proportional to 1,278.80, 1,764.36 and 781.32

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Solution

The fourth proportional to 1,278.80, 1,764.36 and 781.32 is: 1,077.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.80 : 1,764.36 = 781.32 : x
  2. Step 2: Convert to fraction form
    1,278.80/1,764.36 = 781.32/x
  3. Step 3: Cross multiply
    1,278.80x = 1,764.36 × 781.32
  4. Step 4: Simplify right side
    1,278.80x = 1,378,529.76
  5. Step 5: Solve for x
    x = 1,378,529.76/1,278.80
  6. Step 6: Final answer
    x = 1,077.99

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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.