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Finding the Fourth Proportional to 113.81, 156.91 and 78.78

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Solution

The fourth proportional to 113.81, 156.91 and 78.78 is: 108.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    113.81 : 156.91 = 78.78 : x
  2. Step 2: Convert to fraction form
    113.81/156.91 = 78.78/x
  3. Step 3: Cross multiply
    113.81x = 156.91 × 78.78
  4. Step 4: Simplify right side
    113.81x = 12,361.37
  5. Step 5: Solve for x
    x = 12,361.37/113.81
  6. Step 6: Final answer
    x = 108.61

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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.