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Finding the Fourth Proportional to 78.99, 109.11 and 78.39

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Solution

The fourth proportional to 78.99, 109.11 and 78.39 is: 108.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.99 : 109.11 = 78.39 : x
  2. Step 2: Convert to fraction form
    78.99/109.11 = 78.39/x
  3. Step 3: Cross multiply
    78.99x = 109.11 × 78.39
  4. Step 4: Simplify right side
    78.99x = 8,553.13
  5. Step 5: Solve for x
    x = 8,553.13/78.99
  6. Step 6: Final answer
    x = 108.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.