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Finding the Fourth Proportional to 221.65, 306.07 and 138.90

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Solution

The fourth proportional to 221.65, 306.07 and 138.90 is: 191.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.65 : 306.07 = 138.90 : x
  2. Step 2: Convert to fraction form
    221.65/306.07 = 138.90/x
  3. Step 3: Cross multiply
    221.65x = 306.07 × 138.90
  4. Step 4: Simplify right side
    221.65x = 42,513.43
  5. Step 5: Solve for x
    x = 42,513.43/221.65
  6. Step 6: Final answer
    x = 191.80

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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.