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Finding the Fourth Proportional to 82.90, 115.09 and 78.04

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Solution

The fourth proportional to 82.90, 115.09 and 78.04 is: 108.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.90 : 115.09 = 78.04 : x
  2. Step 2: Convert to fraction form
    82.90/115.09 = 78.04/x
  3. Step 3: Cross multiply
    82.90x = 115.09 × 78.04
  4. Step 4: Simplify right side
    82.90x = 8,981.62
  5. Step 5: Solve for x
    x = 8,981.62/82.90
  6. Step 6: Final answer
    x = 108.34

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.