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Finding the Fourth Proportional to 111.12, 166.40 and 78.65

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Solution

The fourth proportional to 111.12, 166.40 and 78.65 is: 117.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.12 : 166.40 = 78.65 : x
  2. Step 2: Convert to fraction form
    111.12/166.40 = 78.65/x
  3. Step 3: Cross multiply
    111.12x = 166.40 × 78.65
  4. Step 4: Simplify right side
    111.12x = 13,086.97
  5. Step 5: Solve for x
    x = 13,086.97/111.12
  6. Step 6: Final answer
    x = 117.77

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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.