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Finding the Fourth Proportional to 686.89, 1,028.97 and 638.90

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Solution

The fourth proportional to 686.89, 1,028.97 and 638.90 is: 957.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.89 : 1,028.97 = 638.90 : x
  2. Step 2: Convert to fraction form
    686.89/1,028.97 = 638.90/x
  3. Step 3: Cross multiply
    686.89x = 1,028.97 × 638.90
  4. Step 4: Simplify right side
    686.89x = 657,407.65
  5. Step 5: Solve for x
    x = 657,407.65/686.89
  6. Step 6: Final answer
    x = 957.08

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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.