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Finding the Fourth Proportional to 687.65, 1,028.88 and 408.98

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Solution

The fourth proportional to 687.65, 1,028.88 and 408.98 is: 611.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.65 : 1,028.88 = 408.98 : x
  2. Step 2: Convert to fraction form
    687.65/1,028.88 = 408.98/x
  3. Step 3: Cross multiply
    687.65x = 1,028.88 × 408.98
  4. Step 4: Simplify right side
    687.65x = 420,786.20
  5. Step 5: Solve for x
    x = 420,786.20/687.65
  6. Step 6: Final answer
    x = 611.92

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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.