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Finding the Fourth Proportional to 81.50, 121.65 and 77.51

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Solution

The fourth proportional to 81.50, 121.65 and 77.51 is: 115.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.50 : 121.65 = 77.51 : x
  2. Step 2: Convert to fraction form
    81.50/121.65 = 77.51/x
  3. Step 3: Cross multiply
    81.50x = 121.65 × 77.51
  4. Step 4: Simplify right side
    81.50x = 9,428.48
  5. Step 5: Solve for x
    x = 9,428.48/81.50
  6. Step 6: Final answer
    x = 115.69

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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.