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Finding the Fourth Proportional to 1,139.44, 1,709.10 and 399

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Solution

The fourth proportional to 1,139.44, 1,709.10 and 399 is: 598.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.44 : 1,709.10 = 399 : x
  2. Step 2: Convert to fraction form
    1,139.44/1,709.10 = 399/x
  3. Step 3: Cross multiply
    1,139.44x = 1,709.10 × 399
  4. Step 4: Simplify right side
    1,139.44x = 681,930.90
  5. Step 5: Solve for x
    x = 681,930.90/1,139.44
  6. Step 6: Final answer
    x = 598.48

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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.