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Finding the Fourth Proportional to 111.97, 154.47 and 87.31

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Solution

The fourth proportional to 111.97, 154.47 and 87.31 is: 120.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.97 : 154.47 = 87.31 : x
  2. Step 2: Convert to fraction form
    111.97/154.47 = 87.31/x
  3. Step 3: Cross multiply
    111.97x = 154.47 × 87.31
  4. Step 4: Simplify right side
    111.97x = 13,486.78
  5. Step 5: Solve for x
    x = 13,486.78/111.97
  6. Step 6: Final answer
    x = 120.45

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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.