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Finding the Fourth Proportional to 1,120.87, 1,680.81 and 389.94

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Solution

The fourth proportional to 1,120.87, 1,680.81 and 389.94 is: 584.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.87 : 1,680.81 = 389.94 : x
  2. Step 2: Convert to fraction form
    1,120.87/1,680.81 = 389.94/x
  3. Step 3: Cross multiply
    1,120.87x = 1,680.81 × 389.94
  4. Step 4: Simplify right side
    1,120.87x = 655,415.05
  5. Step 5: Solve for x
    x = 655,415.05/1,120.87
  6. Step 6: Final answer
    x = 584.74

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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.