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Finding the Fourth Proportional to 121.91, 168.26 and 78.26

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Solution

The fourth proportional to 121.91, 168.26 and 78.26 is: 108.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.91 : 168.26 = 78.26 : x
  2. Step 2: Convert to fraction form
    121.91/168.26 = 78.26/x
  3. Step 3: Cross multiply
    121.91x = 168.26 × 78.26
  4. Step 4: Simplify right side
    121.91x = 13,166.80
  5. Step 5: Solve for x
    x = 13,166.80/121.91
  6. Step 6: Final answer
    x = 108.01

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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.