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Finding the Fourth Proportional to 685.40, 1,028.52 and 660.30

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Solution

The fourth proportional to 685.40, 1,028.52 and 660.30 is: 990.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.40 : 1,028.52 = 660.30 : x
  2. Step 2: Convert to fraction form
    685.40/1,028.52 = 660.30/x
  3. Step 3: Cross multiply
    685.40x = 1,028.52 × 660.30
  4. Step 4: Simplify right side
    685.40x = 679,131.76
  5. Step 5: Solve for x
    x = 679,131.76/685.40
  6. Step 6: Final answer
    x = 990.85

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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.