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Finding the Fourth Proportional to 121.74, 168.04 and 78.06

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Solution

The fourth proportional to 121.74, 168.04 and 78.06 is: 107.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.74 : 168.04 = 78.06 : x
  2. Step 2: Convert to fraction form
    121.74/168.04 = 78.06/x
  3. Step 3: Cross multiply
    121.74x = 168.04 × 78.06
  4. Step 4: Simplify right side
    121.74x = 13,117.93
  5. Step 5: Solve for x
    x = 13,117.93/121.74
  6. Step 6: Final answer
    x = 107.76

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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.