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Finding the Fourth Proportional to 86.09, 128.90 and 55.58

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Solution

The fourth proportional to 86.09, 128.90 and 55.58 is: 83.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.09 : 128.90 = 55.58 : x
  2. Step 2: Convert to fraction form
    86.09/128.90 = 55.58/x
  3. Step 3: Cross multiply
    86.09x = 128.90 × 55.58
  4. Step 4: Simplify right side
    86.09x = 7,164.72
  5. Step 5: Solve for x
    x = 7,164.72/86.09
  6. Step 6: Final answer
    x = 83.22

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.