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Finding the Fourth Proportional to 86.74, 129.30 and 86.62

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Solution

The fourth proportional to 86.74, 129.30 and 86.62 is: 129.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.74 : 129.30 = 86.62 : x
  2. Step 2: Convert to fraction form
    86.74/129.30 = 86.62/x
  3. Step 3: Cross multiply
    86.74x = 129.30 × 86.62
  4. Step 4: Simplify right side
    86.74x = 11,199.97
  5. Step 5: Solve for x
    x = 11,199.97/86.74
  6. Step 6: Final answer
    x = 129.12

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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.