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Finding the Fourth Proportional to 113.78, 156.90 and 81.02

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Solution

The fourth proportional to 113.78, 156.90 and 81.02 is: 111.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    113.78 : 156.90 = 81.02 : x
  2. Step 2: Convert to fraction form
    113.78/156.90 = 81.02/x
  3. Step 3: Cross multiply
    113.78x = 156.90 × 81.02
  4. Step 4: Simplify right side
    113.78x = 12,712.04
  5. Step 5: Solve for x
    x = 12,712.04/113.78
  6. Step 6: Final answer
    x = 111.72

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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.