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Finding the Fourth Proportional to 111.65, 154.04 and 78.89

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Solution

The fourth proportional to 111.65, 154.04 and 78.89 is: 108.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.65 : 154.04 = 78.89 : x
  2. Step 2: Convert to fraction form
    111.65/154.04 = 78.89/x
  3. Step 3: Cross multiply
    111.65x = 154.04 × 78.89
  4. Step 4: Simplify right side
    111.65x = 12,151.05
  5. Step 5: Solve for x
    x = 12,151.05/111.65
  6. Step 6: Final answer
    x = 108.84

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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.