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Finding the Fourth Proportional to 85.86, 128.07 and 82.89

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Solution

The fourth proportional to 85.86, 128.07 and 82.89 is: 123.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.86 : 128.07 = 82.89 : x
  2. Step 2: Convert to fraction form
    85.86/128.07 = 82.89/x
  3. Step 3: Cross multiply
    85.86x = 128.07 × 82.89
  4. Step 4: Simplify right side
    85.86x = 10,615.72
  5. Step 5: Solve for x
    x = 10,615.72/85.86
  6. Step 6: Final answer
    x = 123.64

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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.