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Finding the Fourth Proportional to 687.80, 1,039.82 and 687.80

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Solution

The fourth proportional to 687.80, 1,039.82 and 687.80 is: 1,039.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.80 : 1,039.82 = 687.80 : x
  2. Step 2: Convert to fraction form
    687.80/1,039.82 = 687.80/x
  3. Step 3: Cross multiply
    687.80x = 1,039.82 × 687.80
  4. Step 4: Simplify right side
    687.80x = 715,188.20
  5. Step 5: Solve for x
    x = 715,188.20/687.80
  6. Step 6: Final answer
    x = 1,039.82

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.