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Finding the Fourth Proportional to 687.66, 1,028.90 and 423.19

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Solution

The fourth proportional to 687.66, 1,028.90 and 423.19 is: 633.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.66 : 1,028.90 = 423.19 : x
  2. Step 2: Convert to fraction form
    687.66/1,028.90 = 423.19/x
  3. Step 3: Cross multiply
    687.66x = 1,028.90 × 423.19
  4. Step 4: Simplify right side
    687.66x = 435,422.54
  5. Step 5: Solve for x
    x = 435,422.54/687.66
  6. Step 6: Final answer
    x = 633.20

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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.