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Finding the Fourth Proportional to 438.12, 656.78 and 221.45

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Solution

The fourth proportional to 438.12, 656.78 and 221.45 is: 331.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    438.12 : 656.78 = 221.45 : x
  2. Step 2: Convert to fraction form
    438.12/656.78 = 221.45/x
  3. Step 3: Cross multiply
    438.12x = 656.78 × 221.45
  4. Step 4: Simplify right side
    438.12x = 145,439.54
  5. Step 5: Solve for x
    x = 145,439.54/438.12
  6. Step 6: Final answer
    x = 331.96

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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.