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Finding the Fourth Proportional to 1,391.72, 2,086.14 and 660.74

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Solution

The fourth proportional to 1,391.72, 2,086.14 and 660.74 is: 990.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.72 : 2,086.14 = 660.74 : x
  2. Step 2: Convert to fraction form
    1,391.72/2,086.14 = 660.74/x
  3. Step 3: Cross multiply
    1,391.72x = 2,086.14 × 660.74
  4. Step 4: Simplify right side
    1,391.72x = 1,378,396.14
  5. Step 5: Solve for x
    x = 1,378,396.14/1,391.72
  6. Step 6: Final answer
    x = 990.43

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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.