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Finding the Fourth Proportional to 665.80, 999.90 and 644.20

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Solution

The fourth proportional to 665.80, 999.90 and 644.20 is: 967.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.80 : 999.90 = 644.20 : x
  2. Step 2: Convert to fraction form
    665.80/999.90 = 644.20/x
  3. Step 3: Cross multiply
    665.80x = 999.90 × 644.20
  4. Step 4: Simplify right side
    665.80x = 644,135.58
  5. Step 5: Solve for x
    x = 644,135.58/665.80
  6. Step 6: Final answer
    x = 967.46

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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.