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Finding the Fourth Proportional to 84.20, 126.36 and 76.64

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Solution

The fourth proportional to 84.20, 126.36 and 76.64 is: 115.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.20 : 126.36 = 76.64 : x
  2. Step 2: Convert to fraction form
    84.20/126.36 = 76.64/x
  3. Step 3: Cross multiply
    84.20x = 126.36 × 76.64
  4. Step 4: Simplify right side
    84.20x = 9,684.23
  5. Step 5: Solve for x
    x = 9,684.23/84.20
  6. Step 6: Final answer
    x = 115.01

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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.