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Finding the Fourth Proportional to 137.80, 206.70 and 121.78

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Solution

The fourth proportional to 137.80, 206.70 and 121.78 is: 182.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.80 : 206.70 = 121.78 : x
  2. Step 2: Convert to fraction form
    137.80/206.70 = 121.78/x
  3. Step 3: Cross multiply
    137.80x = 206.70 × 121.78
  4. Step 4: Simplify right side
    137.80x = 25,171.93
  5. Step 5: Solve for x
    x = 25,171.93/137.80
  6. Step 6: Final answer
    x = 182.67

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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.