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Finding the Fourth Proportional to 86.71, 129.84 and 61.09

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Solution

The fourth proportional to 86.71, 129.84 and 61.09 is: 91.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.71 : 129.84 = 61.09 : x
  2. Step 2: Convert to fraction form
    86.71/129.84 = 61.09/x
  3. Step 3: Cross multiply
    86.71x = 129.84 × 61.09
  4. Step 4: Simplify right side
    86.71x = 7,931.93
  5. Step 5: Solve for x
    x = 7,931.93/86.71
  6. Step 6: Final answer
    x = 91.48

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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.