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Finding the Fourth Proportional to 1,207.53, 1,811.55 and 687.78

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Solution

The fourth proportional to 1,207.53, 1,811.55 and 687.78 is: 1,031.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,207.53 : 1,811.55 = 687.78 : x
  2. Step 2: Convert to fraction form
    1,207.53/1,811.55 = 687.78/x
  3. Step 3: Cross multiply
    1,207.53x = 1,811.55 × 687.78
  4. Step 4: Simplify right side
    1,207.53x = 1,245,947.86
  5. Step 5: Solve for x
    x = 1,245,947.86/1,207.53
  6. Step 6: Final answer
    x = 1,031.82

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.