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Finding the Fourth Proportional to 138.71, 191.40 and 79.68

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Solution

The fourth proportional to 138.71, 191.40 and 79.68 is: 109.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.71 : 191.40 = 79.68 : x
  2. Step 2: Convert to fraction form
    138.71/191.40 = 79.68/x
  3. Step 3: Cross multiply
    138.71x = 191.40 × 79.68
  4. Step 4: Simplify right side
    138.71x = 15,250.95
  5. Step 5: Solve for x
    x = 15,250.95/138.71
  6. Step 6: Final answer
    x = 109.95

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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.