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Finding the Fourth Proportional to 84.24, 126.81 and 76.80

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Solution

The fourth proportional to 84.24, 126.81 and 76.80 is: 115.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.24 : 126.81 = 76.80 : x
  2. Step 2: Convert to fraction form
    84.24/126.81 = 76.80/x
  3. Step 3: Cross multiply
    84.24x = 126.81 × 76.80
  4. Step 4: Simplify right side
    84.24x = 9,739.01
  5. Step 5: Solve for x
    x = 9,739.01/84.24
  6. Step 6: Final answer
    x = 115.61

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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.