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Finding the Fourth Proportional to 86.64, 129.24 and 84.12

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Solution

The fourth proportional to 86.64, 129.24 and 84.12 is: 125.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.64 : 129.24 = 84.12 : x
  2. Step 2: Convert to fraction form
    86.64/129.24 = 84.12/x
  3. Step 3: Cross multiply
    86.64x = 129.24 × 84.12
  4. Step 4: Simplify right side
    86.64x = 10,871.67
  5. Step 5: Solve for x
    x = 10,871.67/86.64
  6. Step 6: Final answer
    x = 125.48

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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.