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Finding the Fourth Proportional to 86.16, 128.36 and 82

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Solution

The fourth proportional to 86.16, 128.36 and 82 is: 122.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.16 : 128.36 = 82 : x
  2. Step 2: Convert to fraction form
    86.16/128.36 = 82/x
  3. Step 3: Cross multiply
    86.16x = 128.36 × 82
  4. Step 4: Simplify right side
    86.16x = 10,525.52
  5. Step 5: Solve for x
    x = 10,525.52/86.16
  6. Step 6: Final answer
    x = 122.16

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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.