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Finding the Fourth Proportional to 81.15, 121.50 and 69

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Solution

The fourth proportional to 81.15, 121.50 and 69 is: 103.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.15 : 121.50 = 69 : x
  2. Step 2: Convert to fraction form
    81.15/121.50 = 69/x
  3. Step 3: Cross multiply
    81.15x = 121.50 × 69
  4. Step 4: Simplify right side
    81.15x = 8,383.50
  5. Step 5: Solve for x
    x = 8,383.50/81.15
  6. Step 6: Final answer
    x = 103.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.