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Finding the Fourth Proportional to 1,387, 2,080.52 and 399.85

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Solution

The fourth proportional to 1,387, 2,080.52 and 399.85 is: 599.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387 : 2,080.52 = 399.85 : x
  2. Step 2: Convert to fraction form
    1,387/2,080.52 = 399.85/x
  3. Step 3: Cross multiply
    1,387x = 2,080.52 × 399.85
  4. Step 4: Simplify right side
    1,387x = 831,895.92
  5. Step 5: Solve for x
    x = 831,895.92/1,387
  6. Step 6: Final answer
    x = 599.78

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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.