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Finding the Fourth Proportional to 86.64, 129.32 and 77.64

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Solution

The fourth proportional to 86.64, 129.32 and 77.64 is: 115.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.64 : 129.32 = 77.64 : x
  2. Step 2: Convert to fraction form
    86.64/129.32 = 77.64/x
  3. Step 3: Cross multiply
    86.64x = 129.32 × 77.64
  4. Step 4: Simplify right side
    86.64x = 10,040.02
  5. Step 5: Solve for x
    x = 10,040.02/86.64
  6. Step 6: Final answer
    x = 115.88

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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.