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Finding the Fourth Proportional to 122.15, 168.30 and 87.21

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Solution

The fourth proportional to 122.15, 168.30 and 87.21 is: 120.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.15 : 168.30 = 87.21 : x
  2. Step 2: Convert to fraction form
    122.15/168.30 = 87.21/x
  3. Step 3: Cross multiply
    122.15x = 168.30 × 87.21
  4. Step 4: Simplify right side
    122.15x = 14,677.44
  5. Step 5: Solve for x
    x = 14,677.44/122.15
  6. Step 6: Final answer
    x = 120.16

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.