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Finding the Fourth Proportional to 86.08, 128.32 and 85.76

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Solution

The fourth proportional to 86.08, 128.32 and 85.76 is: 127.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.08 : 128.32 = 85.76 : x
  2. Step 2: Convert to fraction form
    86.08/128.32 = 85.76/x
  3. Step 3: Cross multiply
    86.08x = 128.32 × 85.76
  4. Step 4: Simplify right side
    86.08x = 11,004.72
  5. Step 5: Solve for x
    x = 11,004.72/86.08
  6. Step 6: Final answer
    x = 127.84

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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.