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Finding the Fourth Proportional to 86.46, 128.73 and 85.16

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Solution

The fourth proportional to 86.46, 128.73 and 85.16 is: 126.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.46 : 128.73 = 85.16 : x
  2. Step 2: Convert to fraction form
    86.46/128.73 = 85.16/x
  3. Step 3: Cross multiply
    86.46x = 128.73 × 85.16
  4. Step 4: Simplify right side
    86.46x = 10,962.65
  5. Step 5: Solve for x
    x = 10,962.65/86.46
  6. Step 6: Final answer
    x = 126.79

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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.