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Finding the Fourth Proportional to 86.97, 129.78 and 84.81

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Solution

The fourth proportional to 86.97, 129.78 and 84.81 is: 126.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.97 : 129.78 = 84.81 : x
  2. Step 2: Convert to fraction form
    86.97/129.78 = 84.81/x
  3. Step 3: Cross multiply
    86.97x = 129.78 × 84.81
  4. Step 4: Simplify right side
    86.97x = 11,006.64
  5. Step 5: Solve for x
    x = 11,006.64/86.97
  6. Step 6: Final answer
    x = 126.56

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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.