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Finding the Fourth Proportional to 111.20, 153.30 and 81.72

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Solution

The fourth proportional to 111.20, 153.30 and 81.72 is: 112.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.20 : 153.30 = 81.72 : x
  2. Step 2: Convert to fraction form
    111.20/153.30 = 81.72/x
  3. Step 3: Cross multiply
    111.20x = 153.30 × 81.72
  4. Step 4: Simplify right side
    111.20x = 12,527.68
  5. Step 5: Solve for x
    x = 12,527.68/111.20
  6. Step 6: Final answer
    x = 112.66

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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.