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Finding the Fourth Proportional to 81.40, 121.52 and 69.16

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Solution

The fourth proportional to 81.40, 121.52 and 69.16 is: 103.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.40 : 121.52 = 69.16 : x
  2. Step 2: Convert to fraction form
    81.40/121.52 = 69.16/x
  3. Step 3: Cross multiply
    81.40x = 121.52 × 69.16
  4. Step 4: Simplify right side
    81.40x = 8,404.32
  5. Step 5: Solve for x
    x = 8,404.32/81.40
  6. Step 6: Final answer
    x = 103.25

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.