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Finding the Fourth Proportional to 1,139.78, 1,572.97 and 642.44

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Solution

The fourth proportional to 1,139.78, 1,572.97 and 642.44 is: 886.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.78 : 1,572.97 = 642.44 : x
  2. Step 2: Convert to fraction form
    1,139.78/1,572.97 = 642.44/x
  3. Step 3: Cross multiply
    1,139.78x = 1,572.97 × 642.44
  4. Step 4: Simplify right side
    1,139.78x = 1,010,538.85
  5. Step 5: Solve for x
    x = 1,010,538.85/1,139.78
  6. Step 6: Final answer
    x = 886.61

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.