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Finding the Fourth Proportional to 103.91, 142.96 and 79.20

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Solution

The fourth proportional to 103.91, 142.96 and 79.20 is: 108.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.91 : 142.96 = 79.20 : x
  2. Step 2: Convert to fraction form
    103.91/142.96 = 79.20/x
  3. Step 3: Cross multiply
    103.91x = 142.96 × 79.20
  4. Step 4: Simplify right side
    103.91x = 11,322.43
  5. Step 5: Solve for x
    x = 11,322.43/103.91
  6. Step 6: Final answer
    x = 108.96

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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.