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Finding the Fourth Proportional to 1,280.87, 1,767.65 and 721.56

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Solution

The fourth proportional to 1,280.87, 1,767.65 and 721.56 is: 995.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.87 : 1,767.65 = 721.56 : x
  2. Step 2: Convert to fraction form
    1,280.87/1,767.65 = 721.56/x
  3. Step 3: Cross multiply
    1,280.87x = 1,767.65 × 721.56
  4. Step 4: Simplify right side
    1,280.87x = 1,275,465.53
  5. Step 5: Solve for x
    x = 1,275,465.53/1,280.87
  6. Step 6: Final answer
    x = 995.78

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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.