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Finding the Fourth Proportional to 1,139.62, 1,707.85 and 521.78

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Solution

The fourth proportional to 1,139.62, 1,707.85 and 521.78 is: 781.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.62 : 1,707.85 = 521.78 : x
  2. Step 2: Convert to fraction form
    1,139.62/1,707.85 = 521.78/x
  3. Step 3: Cross multiply
    1,139.62x = 1,707.85 × 521.78
  4. Step 4: Simplify right side
    1,139.62x = 891,121.97
  5. Step 5: Solve for x
    x = 891,121.97/1,139.62
  6. Step 6: Final answer
    x = 781.95

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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.