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Finding the Fourth Proportional to 1,247.20, 1,721.06 and 687.68

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Solution

The fourth proportional to 1,247.20, 1,721.06 and 687.68 is: 948.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.20 : 1,721.06 = 687.68 : x
  2. Step 2: Convert to fraction form
    1,247.20/1,721.06 = 687.68/x
  3. Step 3: Cross multiply
    1,247.20x = 1,721.06 × 687.68
  4. Step 4: Simplify right side
    1,247.20x = 1,183,530.37
  5. Step 5: Solve for x
    x = 1,183,530.37/1,247.20
  6. Step 6: Final answer
    x = 948.95

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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.