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Finding the Fourth Proportional to 221.49, 305.78 and 138.68

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Solution

The fourth proportional to 221.49, 305.78 and 138.68 is: 191.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.49 : 305.78 = 138.68 : x
  2. Step 2: Convert to fraction form
    221.49/305.78 = 138.68/x
  3. Step 3: Cross multiply
    221.49x = 305.78 × 138.68
  4. Step 4: Simplify right side
    221.49x = 42,403.35
  5. Step 5: Solve for x
    x = 42,403.35/221.49
  6. Step 6: Final answer
    x = 191.45

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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.