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Finding the Fourth Proportional to 86.81, 129.57 and 74.66

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Solution

The fourth proportional to 86.81, 129.57 and 74.66 is: 111.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.81 : 129.57 = 74.66 : x
  2. Step 2: Convert to fraction form
    86.81/129.57 = 74.66/x
  3. Step 3: Cross multiply
    86.81x = 129.57 × 74.66
  4. Step 4: Simplify right side
    86.81x = 9,672.77
  5. Step 5: Solve for x
    x = 9,672.77/86.81
  6. Step 6: Final answer
    x = 111.43

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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.