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Finding the Fourth Proportional to 122.15, 168.40 and 89

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Solution

The fourth proportional to 122.15, 168.40 and 89 is: 122.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.15 : 168.40 = 89 : x
  2. Step 2: Convert to fraction form
    122.15/168.40 = 89/x
  3. Step 3: Cross multiply
    122.15x = 168.40 × 89
  4. Step 4: Simplify right side
    122.15x = 14,987.60
  5. Step 5: Solve for x
    x = 14,987.60/122.15
  6. Step 6: Final answer
    x = 122.70

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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.