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Finding the Fourth Proportional to 86.22, 129.85 and 77.76

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Solution

The fourth proportional to 86.22, 129.85 and 77.76 is: 117.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.22 : 129.85 = 77.76 : x
  2. Step 2: Convert to fraction form
    86.22/129.85 = 77.76/x
  3. Step 3: Cross multiply
    86.22x = 129.85 × 77.76
  4. Step 4: Simplify right side
    86.22x = 10,096.94
  5. Step 5: Solve for x
    x = 10,096.94/86.22
  6. Step 6: Final answer
    x = 117.11

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.