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Finding the Fourth Proportional to 1,380.87, 2,071.45 and 687.71

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Solution

The fourth proportional to 1,380.87, 2,071.45 and 687.71 is: 1,031.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,380.87 : 2,071.45 = 687.71 : x
  2. Step 2: Convert to fraction form
    1,380.87/2,071.45 = 687.71/x
  3. Step 3: Cross multiply
    1,380.87x = 2,071.45 × 687.71
  4. Step 4: Simplify right side
    1,380.87x = 1,424,546.52
  5. Step 5: Solve for x
    x = 1,424,546.52/1,380.87
  6. Step 6: Final answer
    x = 1,031.63

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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.