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Finding the Fourth Proportional to 111.90, 154.50 and 87.32

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Solution

The fourth proportional to 111.90, 154.50 and 87.32 is: 120.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.90 : 154.50 = 87.32 : x
  2. Step 2: Convert to fraction form
    111.90/154.50 = 87.32/x
  3. Step 3: Cross multiply
    111.90x = 154.50 × 87.32
  4. Step 4: Simplify right side
    111.90x = 13,490.94
  5. Step 5: Solve for x
    x = 13,490.94/111.90
  6. Step 6: Final answer
    x = 120.56

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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.