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Finding the Fourth Proportional to 1,278.90, 1,765.05 and 781.44

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Solution

The fourth proportional to 1,278.90, 1,765.05 and 781.44 is: 1,078.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.90 : 1,765.05 = 781.44 : x
  2. Step 2: Convert to fraction form
    1,278.90/1,765.05 = 781.44/x
  3. Step 3: Cross multiply
    1,278.90x = 1,765.05 × 781.44
  4. Step 4: Simplify right side
    1,278.90x = 1,379,267.94
  5. Step 5: Solve for x
    x = 1,379,267.94/1,278.90
  6. Step 6: Final answer
    x = 1,078.48

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1.5x scale

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.