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Finding the Fourth Proportional to 111.72, 154.20 and 77.28

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Solution

The fourth proportional to 111.72, 154.20 and 77.28 is: 106.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.72 : 154.20 = 77.28 : x
  2. Step 2: Convert to fraction form
    111.72/154.20 = 77.28/x
  3. Step 3: Cross multiply
    111.72x = 154.20 × 77.28
  4. Step 4: Simplify right side
    111.72x = 11,916.58
  5. Step 5: Solve for x
    x = 11,916.58/111.72
  6. Step 6: Final answer
    x = 106.66

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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.