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Finding the Fourth Proportional to 121.68, 182.78 and 81.16

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Solution

The fourth proportional to 121.68, 182.78 and 81.16 is: 121.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.68 : 182.78 = 81.16 : x
  2. Step 2: Convert to fraction form
    121.68/182.78 = 81.16/x
  3. Step 3: Cross multiply
    121.68x = 182.78 × 81.16
  4. Step 4: Simplify right side
    121.68x = 14,834.42
  5. Step 5: Solve for x
    x = 14,834.42/121.68
  6. Step 6: Final answer
    x = 121.91

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.