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Finding the Fourth Proportional to 86.68, 129.34 and 81.51

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Solution

The fourth proportional to 86.68, 129.34 and 81.51 is: 121.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.68 : 129.34 = 81.51 : x
  2. Step 2: Convert to fraction form
    86.68/129.34 = 81.51/x
  3. Step 3: Cross multiply
    86.68x = 129.34 × 81.51
  4. Step 4: Simplify right side
    86.68x = 10,542.50
  5. Step 5: Solve for x
    x = 10,542.50/86.68
  6. Step 6: Final answer
    x = 121.63

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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.