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Finding the Fourth Proportional to 84.21, 126.90 and 80.49

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Solution

The fourth proportional to 84.21, 126.90 and 80.49 is: 121.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.21 : 126.90 = 80.49 : x
  2. Step 2: Convert to fraction form
    84.21/126.90 = 80.49/x
  3. Step 3: Cross multiply
    84.21x = 126.90 × 80.49
  4. Step 4: Simplify right side
    84.21x = 10,214.18
  5. Step 5: Solve for x
    x = 10,214.18/84.21
  6. Step 6: Final answer
    x = 121.29

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.