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Finding the Fourth Proportional to 1,139.90, 1,573.11 and 642.56

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Solution

The fourth proportional to 1,139.90, 1,573.11 and 642.56 is: 886.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.90 : 1,573.11 = 642.56 : x
  2. Step 2: Convert to fraction form
    1,139.90/1,573.11 = 642.56/x
  3. Step 3: Cross multiply
    1,139.90x = 1,573.11 × 642.56
  4. Step 4: Simplify right side
    1,139.90x = 1,010,809.70
  5. Step 5: Solve for x
    x = 1,010,809.70/1,139.90
  6. Step 6: Final answer
    x = 886.75

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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.