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Finding the Fourth Proportional to 660.39, 989.17 and 428.60

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Solution

The fourth proportional to 660.39, 989.17 and 428.60 is: 641.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.39 : 989.17 = 428.60 : x
  2. Step 2: Convert to fraction form
    660.39/989.17 = 428.60/x
  3. Step 3: Cross multiply
    660.39x = 989.17 × 428.60
  4. Step 4: Simplify right side
    660.39x = 423,958.26
  5. Step 5: Solve for x
    x = 423,958.26/660.39
  6. Step 6: Final answer
    x = 641.98

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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.