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Finding the Fourth Proportional to 720.11, 991.68 and 687.31

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Solution

The fourth proportional to 720.11, 991.68 and 687.31 is: 946.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.11 : 991.68 = 687.31 : x
  2. Step 2: Convert to fraction form
    720.11/991.68 = 687.31/x
  3. Step 3: Cross multiply
    720.11x = 991.68 × 687.31
  4. Step 4: Simplify right side
    720.11x = 681,591.58
  5. Step 5: Solve for x
    x = 681,591.58/720.11
  6. Step 6: Final answer
    x = 946.51

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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.