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Finding the Fourth Proportional to 665.40, 996.50 and 421.20

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Solution

The fourth proportional to 665.40, 996.50 and 421.20 is: 630.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.40 : 996.50 = 421.20 : x
  2. Step 2: Convert to fraction form
    665.40/996.50 = 421.20/x
  3. Step 3: Cross multiply
    665.40x = 996.50 × 421.20
  4. Step 4: Simplify right side
    665.40x = 419,725.80
  5. Step 5: Solve for x
    x = 419,725.80/665.40
  6. Step 6: Final answer
    x = 630.79

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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.