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Finding the Fourth Proportional to 687.21, 1,028.96 and 412.91

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Solution

The fourth proportional to 687.21, 1,028.96 and 412.91 is: 618.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.21 : 1,028.96 = 412.91 : x
  2. Step 2: Convert to fraction form
    687.21/1,028.96 = 412.91/x
  3. Step 3: Cross multiply
    687.21x = 1,028.96 × 412.91
  4. Step 4: Simplify right side
    687.21x = 424,867.87
  5. Step 5: Solve for x
    x = 424,867.87/687.21
  6. Step 6: Final answer
    x = 618.25

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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.