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Finding the Fourth Proportional to 113.76, 170.40 and 81.24

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Solution

The fourth proportional to 113.76, 170.40 and 81.24 is: 121.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    113.76 : 170.40 = 81.24 : x
  2. Step 2: Convert to fraction form
    113.76/170.40 = 81.24/x
  3. Step 3: Cross multiply
    113.76x = 170.40 × 81.24
  4. Step 4: Simplify right side
    113.76x = 13,843.30
  5. Step 5: Solve for x
    x = 13,843.30/113.76
  6. Step 6: Final answer
    x = 121.69

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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.