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Finding the Fourth Proportional to 113.55, 170.21 and 86.61

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Solution

The fourth proportional to 113.55, 170.21 and 86.61 is: 129.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    113.55 : 170.21 = 86.61 : x
  2. Step 2: Convert to fraction form
    113.55/170.21 = 86.61/x
  3. Step 3: Cross multiply
    113.55x = 170.21 × 86.61
  4. Step 4: Simplify right side
    113.55x = 14,742.74
  5. Step 5: Solve for x
    x = 14,742.74/113.55
  6. Step 6: Final answer
    x = 129.84

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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.