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Finding the Fourth Proportional to 121.88, 168.19 and 78.22

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Solution

The fourth proportional to 121.88, 168.19 and 78.22 is: 107.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.88 : 168.19 = 78.22 : x
  2. Step 2: Convert to fraction form
    121.88/168.19 = 78.22/x
  3. Step 3: Cross multiply
    121.88x = 168.19 × 78.22
  4. Step 4: Simplify right side
    121.88x = 13,155.21
  5. Step 5: Solve for x
    x = 13,155.21/121.88
  6. Step 6: Final answer
    x = 107.94

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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.