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Finding the Fourth Proportional to 81.24, 121.68 and 77.48

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Solution

The fourth proportional to 81.24, 121.68 and 77.48 is: 116.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.24 : 121.68 = 77.48 : x
  2. Step 2: Convert to fraction form
    81.24/121.68 = 77.48/x
  3. Step 3: Cross multiply
    81.24x = 121.68 × 77.48
  4. Step 4: Simplify right side
    81.24x = 9,427.77
  5. Step 5: Solve for x
    x = 9,427.77/81.24
  6. Step 6: Final answer
    x = 116.05

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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.