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Finding the Fourth Proportional to 645.12, 966.48 and 428.40

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Solution

The fourth proportional to 645.12, 966.48 and 428.40 is: 641.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.12 : 966.48 = 428.40 : x
  2. Step 2: Convert to fraction form
    645.12/966.48 = 428.40/x
  3. Step 3: Cross multiply
    645.12x = 966.48 × 428.40
  4. Step 4: Simplify right side
    645.12x = 414,040.03
  5. Step 5: Solve for x
    x = 414,040.03/645.12
  6. Step 6: Final answer
    x = 641.80

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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.