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Finding the Fourth Proportional to 121.78, 182.76 and 91.43

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Solution

The fourth proportional to 121.78, 182.76 and 91.43 is: 137.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.78 : 182.76 = 91.43 : x
  2. Step 2: Convert to fraction form
    121.78/182.76 = 91.43/x
  3. Step 3: Cross multiply
    121.78x = 182.76 × 91.43
  4. Step 4: Simplify right side
    121.78x = 16,709.06
  5. Step 5: Solve for x
    x = 16,709.06/121.78
  6. Step 6: Final answer
    x = 137.21

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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.