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Finding the Fourth Proportional to 99.12, 136.71 and 78.39

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Solution

The fourth proportional to 99.12, 136.71 and 78.39 is: 108.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.12 : 136.71 = 78.39 : x
  2. Step 2: Convert to fraction form
    99.12/136.71 = 78.39/x
  3. Step 3: Cross multiply
    99.12x = 136.71 × 78.39
  4. Step 4: Simplify right side
    99.12x = 10,716.70
  5. Step 5: Solve for x
    x = 10,716.70/99.12
  6. Step 6: Final answer
    x = 108.12

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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.