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Finding the Fourth Proportional to 86.23, 129.21 and 55.78

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Solution

The fourth proportional to 86.23, 129.21 and 55.78 is: 83.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.23 : 129.21 = 55.78 : x
  2. Step 2: Convert to fraction form
    86.23/129.21 = 55.78/x
  3. Step 3: Cross multiply
    86.23x = 129.21 × 55.78
  4. Step 4: Simplify right side
    86.23x = 7,206.80
  5. Step 5: Solve for x
    x = 7,206.80/86.23
  6. Step 6: Final answer
    x = 83.58

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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.