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Finding the Fourth Proportional to 86.45, 128.66 and 82.69

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Solution

The fourth proportional to 86.45, 128.66 and 82.69 is: 123.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.45 : 128.66 = 82.69 : x
  2. Step 2: Convert to fraction form
    86.45/128.66 = 82.69/x
  3. Step 3: Cross multiply
    86.45x = 128.66 × 82.69
  4. Step 4: Simplify right side
    86.45x = 10,638.16
  5. Step 5: Solve for x
    x = 10,638.16/86.45
  6. Step 6: Final answer
    x = 123.06

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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.