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Finding the Fourth Proportional to 86.16, 129.36 and 57.18

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Solution

The fourth proportional to 86.16, 129.36 and 57.18 is: 85.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.16 : 129.36 = 57.18 : x
  2. Step 2: Convert to fraction form
    86.16/129.36 = 57.18/x
  3. Step 3: Cross multiply
    86.16x = 129.36 × 57.18
  4. Step 4: Simplify right side
    86.16x = 7,396.80
  5. Step 5: Solve for x
    x = 7,396.80/86.16
  6. Step 6: Final answer
    x = 85.85

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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.