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Finding the Fourth Proportional to 79.40, 108.57 and 78.92

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Solution

The fourth proportional to 79.40, 108.57 and 78.92 is: 107.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.40 : 108.57 = 78.92 : x
  2. Step 2: Convert to fraction form
    79.40/108.57 = 78.92/x
  3. Step 3: Cross multiply
    79.40x = 108.57 × 78.92
  4. Step 4: Simplify right side
    79.40x = 8,568.34
  5. Step 5: Solve for x
    x = 8,568.34/79.40
  6. Step 6: Final answer
    x = 107.91

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.