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Finding the Fourth Proportional to 221.61, 305.85 and 138.78

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Solution

The fourth proportional to 221.61, 305.85 and 138.78 is: 191.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.61 : 305.85 = 138.78 : x
  2. Step 2: Convert to fraction form
    221.61/305.85 = 138.78/x
  3. Step 3: Cross multiply
    221.61x = 305.85 × 138.78
  4. Step 4: Simplify right side
    221.61x = 42,445.86
  5. Step 5: Solve for x
    x = 42,445.86/221.61
  6. Step 6: Final answer
    x = 191.53

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.