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Finding the Fourth Proportional to 111.20, 166.80 and 78.80

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Solution

The fourth proportional to 111.20, 166.80 and 78.80 is: 118.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.20 : 166.80 = 78.80 : x
  2. Step 2: Convert to fraction form
    111.20/166.80 = 78.80/x
  3. Step 3: Cross multiply
    111.20x = 166.80 × 78.80
  4. Step 4: Simplify right side
    111.20x = 13,143.84
  5. Step 5: Solve for x
    x = 13,143.84/111.20
  6. Step 6: Final answer
    x = 118.20

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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.