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Finding the Fourth Proportional to 111.91, 154.31 and 79.15

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Solution

The fourth proportional to 111.91, 154.31 and 79.15 is: 109.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.91 : 154.31 = 79.15 : x
  2. Step 2: Convert to fraction form
    111.91/154.31 = 79.15/x
  3. Step 3: Cross multiply
    111.91x = 154.31 × 79.15
  4. Step 4: Simplify right side
    111.91x = 12,213.06
  5. Step 5: Solve for x
    x = 12,213.06/111.91
  6. Step 6: Final answer
    x = 109.14

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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.