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Finding the Fourth Proportional to 81.64, 121.64 and 77.52

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Solution

The fourth proportional to 81.64, 121.64 and 77.52 is: 115.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.64 : 121.64 = 77.52 : x
  2. Step 2: Convert to fraction form
    81.64/121.64 = 77.52/x
  3. Step 3: Cross multiply
    81.64x = 121.64 × 77.52
  4. Step 4: Simplify right side
    81.64x = 9,429.53
  5. Step 5: Solve for x
    x = 9,429.53/81.64
  6. Step 6: Final answer
    x = 115.50

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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.