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Finding the Fourth Proportional to 85.86, 128.02 and 84.79

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Solution

The fourth proportional to 85.86, 128.02 and 84.79 is: 126.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.86 : 128.02 = 84.79 : x
  2. Step 2: Convert to fraction form
    85.86/128.02 = 84.79/x
  3. Step 3: Cross multiply
    85.86x = 128.02 × 84.79
  4. Step 4: Simplify right side
    85.86x = 10,854.39
  5. Step 5: Solve for x
    x = 10,854.39/85.86
  6. Step 6: Final answer
    x = 126.43

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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.