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Finding the Fourth Proportional to 84.08, 126.75 and 78.20

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Solution

The fourth proportional to 84.08, 126.75 and 78.20 is: 117.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.08 : 126.75 = 78.20 : x
  2. Step 2: Convert to fraction form
    84.08/126.75 = 78.20/x
  3. Step 3: Cross multiply
    84.08x = 126.75 × 78.20
  4. Step 4: Simplify right side
    84.08x = 9,912.41
  5. Step 5: Solve for x
    x = 9,912.41/84.08
  6. Step 6: Final answer
    x = 117.90

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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.