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Finding the Fourth Proportional to 105.78, 158.79 and 78.90

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Solution

The fourth proportional to 105.78, 158.79 and 78.90 is: 118.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.78 : 158.79 = 78.90 : x
  2. Step 2: Convert to fraction form
    105.78/158.79 = 78.90/x
  3. Step 3: Cross multiply
    105.78x = 158.79 × 78.90
  4. Step 4: Simplify right side
    105.78x = 12,528.01
  5. Step 5: Solve for x
    x = 12,528.01/105.78
  6. Step 6: Final answer
    x = 118.43

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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.