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Finding the Fourth Proportional to 660.17, 989.12 and 428.78

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Solution

The fourth proportional to 660.17, 989.12 and 428.78 is: 642.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.17 : 989.12 = 428.78 : x
  2. Step 2: Convert to fraction form
    660.17/989.12 = 428.78/x
  3. Step 3: Cross multiply
    660.17x = 989.12 × 428.78
  4. Step 4: Simplify right side
    660.17x = 424,118.42
  5. Step 5: Solve for x
    x = 424,118.42/660.17
  6. Step 6: Final answer
    x = 642.44

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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.