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Finding the Fourth Proportional to 1,221.78, 1,832.67 and 643.98

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Solution

The fourth proportional to 1,221.78, 1,832.67 and 643.98 is: 965.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.78 : 1,832.67 = 643.98 : x
  2. Step 2: Convert to fraction form
    1,221.78/1,832.67 = 643.98/x
  3. Step 3: Cross multiply
    1,221.78x = 1,832.67 × 643.98
  4. Step 4: Simplify right side
    1,221.78x = 1,180,202.83
  5. Step 5: Solve for x
    x = 1,180,202.83/1,221.78
  6. Step 6: Final answer
    x = 965.97

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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.