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Finding the Fourth Proportional to 121.72, 167.91 and 77.39

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Solution

The fourth proportional to 121.72, 167.91 and 77.39 is: 106.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.72 : 167.91 = 77.39 : x
  2. Step 2: Convert to fraction form
    121.72/167.91 = 77.39/x
  3. Step 3: Cross multiply
    121.72x = 167.91 × 77.39
  4. Step 4: Simplify right side
    121.72x = 12,994.55
  5. Step 5: Solve for x
    x = 12,994.55/121.72
  6. Step 6: Final answer
    x = 106.76

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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.