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Finding the Fourth Proportional to 121.81, 168.16 and 83.20

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Solution

The fourth proportional to 121.81, 168.16 and 83.20 is: 114.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.81 : 168.16 = 83.20 : x
  2. Step 2: Convert to fraction form
    121.81/168.16 = 83.20/x
  3. Step 3: Cross multiply
    121.81x = 168.16 × 83.20
  4. Step 4: Simplify right side
    121.81x = 13,990.28
  5. Step 5: Solve for x
    x = 13,990.28/121.81
  6. Step 6: Final answer
    x = 114.86

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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.