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Finding the Fourth Proportional to 113.91, 156.80 and 81.11

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Solution

The fourth proportional to 113.91, 156.80 and 81.11 is: 111.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    113.91 : 156.80 = 81.11 : x
  2. Step 2: Convert to fraction form
    113.91/156.80 = 81.11/x
  3. Step 3: Cross multiply
    113.91x = 156.80 × 81.11
  4. Step 4: Simplify right side
    113.91x = 12,718.05
  5. Step 5: Solve for x
    x = 12,718.05/113.91
  6. Step 6: Final answer
    x = 111.65

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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.