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Finding the Fourth Proportional to 138.81, 191.55 and 79.80

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Solution

The fourth proportional to 138.81, 191.55 and 79.80 is: 110.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.81 : 191.55 = 79.80 : x
  2. Step 2: Convert to fraction form
    138.81/191.55 = 79.80/x
  3. Step 3: Cross multiply
    138.81x = 191.55 × 79.80
  4. Step 4: Simplify right side
    138.81x = 15,285.69
  5. Step 5: Solve for x
    x = 15,285.69/138.81
  6. Step 6: Final answer
    x = 110.12

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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.