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Finding the Fourth Proportional to 1,278.67, 1,764.66 and 781.40

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Solution

The fourth proportional to 1,278.67, 1,764.66 and 781.40 is: 1,078.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.67 : 1,764.66 = 781.40 : x
  2. Step 2: Convert to fraction form
    1,278.67/1,764.66 = 781.40/x
  3. Step 3: Cross multiply
    1,278.67x = 1,764.66 × 781.40
  4. Step 4: Simplify right side
    1,278.67x = 1,378,905.83
  5. Step 5: Solve for x
    x = 1,378,905.83/1,278.67
  6. Step 6: Final answer
    x = 1,078.39

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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.