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Finding the Fourth Proportional to 687.71, 1,032.08 and 428.09

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Solution

The fourth proportional to 687.71, 1,032.08 and 428.09 is: 642.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.71 : 1,032.08 = 428.09 : x
  2. Step 2: Convert to fraction form
    687.71/1,032.08 = 428.09/x
  3. Step 3: Cross multiply
    687.71x = 1,032.08 × 428.09
  4. Step 4: Simplify right side
    687.71x = 441,823.13
  5. Step 5: Solve for x
    x = 441,823.13/687.71
  6. Step 6: Final answer
    x = 642.46

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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.